How To Insulate Joist Ends Using Rigid Foam

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Shannon from www.house-improvements.com shows you how to insulate box joist ends in a basement using rigid styrofoam insulation.
If you have questions about your home improvement projects, stop by the forum on our website, where Shannon will answer your questions in detail for free.
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Video © 2016 SKS Media. Videos produced by SKS Media (House-Improvements.com) are provided for informational purposes only. The information contained in the videos is intended to give general guidance to simplify DIY (do it yourself) projects. Because tools, products, materials, equipment, techniques, building codes and local regulations are constantly changing, SKS Media cannot and does not assume any responsibility or liability for the accuracy of the information contained therein. Further, SKS Media will not accept any claim for liability related to, but not limited to, omissions, errors, injury, damage or the outcome of any project. It is the responsibility of the viewer to ensure compliance with all applicable laws, rules, codes and regulations for a project. The viewer must always take proper safety precautions and exercise caution when taking on any project. If there are any questions or doubt in regards to the element of a project, please consult with a licensed professional. SKS Media conducts all matters in accordance with the laws of Saskatchewan, Canada.

[@brettpauley4898]

I ended up doing this in my basement almost exactly as you demonstrated. Wow! What a difference! It's January here in Minnesota and our unfinished basement is very comfortable now. The bedrooms directly above the basement section I worked on also hold their heat much better. For less than $100, I'm sure this will pay itself off in very little time. Thanks for the great video!

[@HouseImprovements]

yes this is a great way to seal things up.

[@alski259]

Sure hope rim joist doesn't rot due to having fiberglass against the rim joist. It WILL trap moisture.

[@laurabarton8265]

Thank you for explaining where and how to insulate rim joists. My rim joists are in a bit of a crevasse from the sill plate (top of foundation wall). And I have been looking for too long on how to seal them. Thank you ( again) !!😊

[@mariaemilianegron]

I love it how simple you make it to be God bless you

[@icberg2glac]

I'm glad I found this.Great video and clear instructions

[@da7heaven]

Good, detailed video. Some recommend putting the foam in first rather than batt insulation.

[@lydialas8756]

@Hello Derek how are you doing

[@acreguy3156]

I agreed. In fact, I'm about to embark on a project like this. I'm thinking of using 2 -2" layers of rigid foam, with the inside one caulking into place with acoustic sealant.

[@ALayne08]

Thanks Shannon for all the help you give.

[@HouseImprovements]

+A Layne your welcome

[@alandouglas104]

Thanks Shannon and Crew!

[@HouseImprovements]

+Alan Douglas Your welcome

[@ronh9384]

Hi Shannon. Good info as always. Maybe you should let people know in the intro that the best way to have questions answered is to use the forum on your website. 😲 Thanks for all you do. Ron

[@jordanhartmann1745]

Just set up a recurring contribution on patreon. thanks for these great vids! every home project i check to see if you have something about it before i start.

[@HouseImprovements]

+Jordan Hartmann Thanks so much!

[@DavidDiepenbrock]

I've done this a few times, and from watching other videos I did something slightly different. I would leave a bit more of a gap around the foam -- more like 3/8", such that the spray foam can be installed across the entire 2" width of the foam board, giving an even tighter seal. I found that cutting the foam slightly larger like this made installation much much easier as well, although it does end up using a few more cans of spray foam.

[@HouseImprovements]

Thanks for sharing!

[@songofthemist7443]

Thank you for the mention about toxicity of the foam products during fires. I have a real problem with the overuse of these products in building because I feel they are contributing to the intensity of fires and the toxicity of the fumes but they are being so pushed for use that it takes a lot of thought and planning to avoid them.

[@percyfaith11]

There are paints or coatings for foams that are meant to provide a flame retardant and cut down on the toxicity and volume of fumes in a fire.

[@acreguy3156]

@@percyfaith11 Agreed. In fact, it's code in Canada that spray foamed "anything" must be protected with a fire retardant material or drywall separated.

[@brettbarager9101]

The hardest part of using cans of spray foam is that the can has to be held mostly vertical and when close to the top, it can be very challenging. The tube on these things is of limited length and flexibility. I have gone to the hardware store and picked up a piece of clear tubing the same size as the cans tube (heat the new tube in hot water to make it pliable and it will fit over the cans tube. When it cools it is very snug!). This allows me more flexibility to get into those nooks and cranies easier. Also, for this vid you did one then the other. I assume you would normally do all the fitting then go back with the spray foam. Good vid

[@HouseImprovements]

Yes small rubber hose works ok as well and yes normally I would fit all the foam and then go and seal them all.

[@redstingraycorvette]

When they built my house they had the fiberglass batting in there and I’ve been told that you need to get rid of the fiberglass and put foam in there and then seal with the spray foam around the edges to seal it and that if you didn’t the air leakage through the fiberglass would cause mold and moisture where it’s cold

[@psmith85channel5]

Do you think just doing the 2" rigid and spray insulation piece over the top sill could provide sufficient/significant insulation (without backfilling with batts)? For example if you had condensation on concrete and didn't want to put batts on there.

[@gary2777]

Thank you for the video; I intend to use the method shown here with the batt insulation and rigid foam. My basement is block wall, would I need to cover and seal the void spaces in the block wall before putting the batt insulation in-between the joists?

[@ThunderDivine]

Thanks for this, I will do this now and use 2 layers of plaster board as a fireproofing. - I will just use foam boards tho. but first some mice mesh cause i found nests at the joist ends.

[@johnbednarski2169]

Hello Shannon. I have a balloon framed home. Can I use this method with this style framing? Thank you.

[@stephaniel2997]

Hi, just wondering if you can infill the embedded joist area with spray foam? Thanks in advance!!

[@thedyslexic9936]

will be cold on the upstairs floor against the base board since you don't have it air sealed with the foam against the outside wall? it looked like you had stuffed some insulation into the gaps below the subfloor, then did the batts and foam.

[@vladb4727]

I'm wondering why there are no videos here combining two methods. Use spray foam just to insulate the rim joists and use foam boards to insulate the walls. Is spray foam fireproof? Also, how would you insulate spots when joists are going in parallel to the concrete wall in the basement? Great videos. Thank you for your hard work!

[@HouseImprovements]

I have an entire playlist of basement finishing and insulating videos:kzbin.info/aero/PLh0KqGKtX4oWUr5nKO6U9y-otNi6OA0ud Most spray foams are not fire proof on their own. Where joists are parallel sometimes you can't even get in there to do anything , but most times what you can do is at least fill that cavity with batt insulation.

[@Ricks2Cents]

I need to do this!!!

[@geojor]

good stuff, thank you ...

[@HouseImprovements]

Thanks

[@MrMuzikAddict]

How do we insulate ductwork plenum? Is the bubble wrap Reflectix stuff any good?

[@cmc4741]

Whats your climate like? Here in Canada it can get very cold and NRCAN has advised insulating cast in rim joists with no more than 1" rigid foam. They say this allows controlled heat loss to keep the joist dry and warm, otherwise the cold will creep in the joist behind the insulation making the floor above very cold and also moisture will seep in and condense causing premature rot of the cast in joist.

[@curiosity2314]

Well on this idea I think I would get the tube in far enough to fill the voids while holding the styro or other in place. Afterwards I would use a scraper to push in and finish. One thing to be said about codes... Do your best to exceed the code requirements whenever possible. Codes are really only in place as a minimum baseline Requirement.

[@Aletsdmj]

I'm starting the project to have a finished basement. First step first. I'll start by insulating the rim joist. This video is awesome and gave a clear direction of what to do and how to. The question is also commented in your video. I'm planning to have an unfinished ceiling, so in the video you mentioned that rigid foam is not recommended to be exposure and will not pass code unless we covered with some "material" (min 7:54). What is the material you talk about: R14 roxul insulation? 2. What type brand of foam you re using? Thank you so much for your videos and response.

[@HouseImprovements]

I'm using XPS foam and Roxul is a rock wool type of insulation that will protect the foam from fire. You could use drywall instead of Roxul but its a lot more work. It would have to be cut to fit and then a fire proof caulking used to seal teh perimeter of each joist bay.

[@stephenwilliams4118]

The foam, is this minimum expansion foam ?

[@garyd3725]

Really curious how you insulated and sealed that window. I’m in the process of doing the same thing and a bit stumped on the correct way of doing it

[@HouseImprovements]

asking questions in our forum is great way for assistance with DIY projects.www.house-improvements.com/forums/

[@jacobusbaas2833]

Best videos😊

[@colleenzuren6399]

Hi Shannon enjoyed your video. Went and bought some xps rigid foam board for rim joist boxes. I have nails protruding how do I take care of nails to place the foam board inside????

[@huejanus5505]

Or bend them over, just be careful not to push them back in

[@sammyagahi6664]

Thank you for your time on preparing the video. I thought insulation is not supposed to be touching furnace ducting at all! Insulations need to have certain clearance from the duct depending on type of the duct, 6" for single layer and 1" for B, eliminating fire hazard and possibility of condensation. What you demonstrated was totally different. Thanks again.

[@HouseImprovements]

These are forced air furnace ducts not chimneys. They do not get hot enough to cause issues.

[@kevvor396]

I appreciate your videos. I have an old building with 30" joist for the ceiling. How would u insulate this ceiling, I can't find insulation that is wide enough. I've found 15", 16", and 24" wide. What is the best way to insulate these wide joist? 15" side by side, spray foam, cutting standard insulation length wise to fit? Please help

[@HouseImprovements]

wow that is a pain. Maybe post this question in my forum and we can discuss this there easier. Please also include in your question wether this is a ceiling on a lower level and the top of the ceiling is a floor above you or if the area above that ceiling is a attic space.www.house-improvements.com/forums/

[@JustDavidK]

Hi! I’m a new subscriber to your channel. Love your contents. I just move to Northern Minnesota from California just this past winter with my family. Got a nice home with an unfinished basement. I’m getting ready to do some work to my basement, but we don’t have enough money at this time to do the entire basement in one sitting. So to ensure that the house could be slightly warmer, I was thinking of simply filling up the rim joist with 2” rigid foam boards only, seal it with spray foam, then cover each slot of rim joist with drywall to keep the foam boards protected in the event of a fire. Would this be a good way to go, or would you have a better suggestion? Thanks.

[@HouseImprovements]

That will help alot, yes. Thanks for subscribing. When you have more questions please use our forum. You will find a link in the description under most of our videos.

[@christianssoldiers4058]

I'm doing a space underneath a garage floor it will have t-bar as the ceiling , how should I do my rim joists ? I'm in b.c. Canada, anuthoughts?

[@bryanmcdermott77]

Shannon, any reason why you put the batt in first and then the 2" foam? I was figuring I would do it opposite in my basement. Does it matter? Thanks, love the vids

[@HouseImprovements]

+bryanmcdermott77 To get the seal above the framed wall were the rest of the vapour barrier is sealed to.You could install foam out at the outer face also if you want to but do not seal it this will allow the space to breath to the exterior.

[@billjonesnation]

@@HouseImprovements perfect. So happy I found this. I was wondering which way to do this. Makes sense to have the vapour barrier of the joist aligned with the vapour barrier of the basement wall.

[@normanwheeler5414]

Shannon, Thank you so much for the video. I just have some questions: First what state was the house in the video? Second have you seen concrete between the joist much? I am from New Jersey and I have not seen that done before. Last have you ever checked an installation after a couple of years? This is a difficult spot to insulate because if you do not have a weather barrier on the exterior i could see moisture build up. I understand the interior rigid to prevent moisture from moving into the space, but depending on the exterior temperature and the location of the dew point I can see a concern

[@normstangl3499]

Norman Wheeler check out building. Science with joe lstiburek.

[@dosadoodle]

We have concrete in our rim joist as well. I'm removing the portions that I can access and air/water sealing the exterior with Siga Fentrum tape, which is vapor open. This means when we fill the rim joist with spray foam, the rim joist can still dry to the exterior. (Water doesn't kill buildings unless it is plentiful or if it can't dry out in a short amount of time, so vapor open tape is important here IMO.)

[@mightymikee1]

If you just put Roxul insulation would you need to cover with a 6mil vapour barrier

[@clmproduces4u]

I've been in a newly renovated basement where there was batt insulation work silver backing on the wall previously. The framers removed the backing in the rim joist spaces, leaving the insulation exposed. The ceiling is also exposed. I have begun having some breathing issues and I believe it's from the insulation exposure. I don't have the funds or time to add block foam so my question is could/should I cut and remove the batt that is in the rim joists? Or is there a quick, inexpensive way to cover each of these joists? Thanks.

[@HouseImprovements]

If the ceiling is exposed you can not use rigid foam and leave it exposed as it needs to be covered by a fire resistant material like roux insulation or drywall. If it is batt insulation it should be covered with a poly vapour barrier and then drywall.

[@clmproduces4u]

HouseImprovements Thanks. I'm going to get some black poly and cover. I just wish there was an easier way than cutting each piece individually.

[@carnini]

Is that a closed type of foam panel so that there will not be moisture issues with moisture wicking through the board (like open cell foam)?

[@HouseImprovements]

Yes this is XPS foam

[@jwb0323]

How can you get the Rockwool to stay on there if the bottom part of your rim Joist isn’t big enough to Hold it

[@merlin3921]

Awesome Video! Should I be using a black caulking on the vapor barrier? Is that just a silicone?

[@HouseImprovements]

use acoustical caulking, it is black or dark grey

[@carlepley1232]

I live in western North Carolina, should I just put 2 inch foam board up against the wooden rim joist or also add the batt insulation in between? I also have concerns if this will void my termite inspection warranty.

[@HouseImprovements]

termites are not an issue here so You would be best to talk to your exterminator .

[@tamarareynolds3658]

So i get why you used the batt above ground, I already have that done in my home - never damp. I have a question about wires - should you spray foam first and cut the rigid around it? Have a lot of weird wiring situations.

[@chinabuffet123]

Is there any concern of the insulation picking up moisture somehow from being tucked directly against the foundation like that?

[@HouseImprovements]

+chinabuffet123 you may get some minor moisture at times but the joist section dries to the exterior just like the walls above it.

[@bpez3106]

Great job. What type of rigid foam did you use. I worked at a habitat site in Oshawa and we had to drywall over the foam to prevent toxic fumes during a fire.

[@HouseImprovements]

Yes if this is exposed and no drywall ceiling it must be cover for fire proofing.

[@HouseImprovements]

That was "Good Stuff" I think

[@lydialas8756]

@Hello How are you doing dear

[@ChristopherAMacleod]

Thanks for this!

[@HouseImprovements]

+Christopher M You're welcome.

[@bulldogbuilders5974]

If you cover the foam board over with Roxul insulation to bring it up to code for fireproofing, would it not make sense just to use the Roxul insulation or because you're filling in such a deep gap, the method being used in this video will be most efficient with added Roxul for fireproofing?

[@HouseImprovements]

The key to the 2" foam is that it is sealed and acts as the vapour barrier as well instead of trying to cut and seal poly in every one of the spaces.

[@gregmarshall7885]

what kind of knife / razor do you use to cut the foam?

[@HouseImprovements]

just a snap off blade style utility knife. Olfa is the type I have

[@pokerswag]

What did you cover it with to pass inspection when using the Owens Corning flammable pink rigid foam insulation?

[@HouseImprovements]

drywall ceiling or Roxul insulation covering the foam.

[@nedcramdon1306]

I just pulled the fiberglass insulation away from the rim joists and they are saturated everywhere (been really cold lately in Canada).Very difficult to dry out until spring (Jan. 1st now). Could I insulate with white 2 1/2" foundation rigid foam over the wet wood and seal with acrylic caulking. I meant to check this years ago, I was afraid to look. Thanks for your patience and great videos.

[@juanjohnrico]

thank you @HouseImprovements! so Roxul, or similar, over rigid foam - left unfinished - could potentially be code compliant where I am in BC, Canada? I am looking to insulate crawlspace walls and joist ends with rigid foam and then ... an easy, cost-effective and code-compliant fire barrier. It is a utility crawl space, and I have no need or desire to finish the space.

[@HouseImprovements]

Because a crawl space is considered a non-living area you may be allowed to use a thinner Roxul or other product. So check your local codes for this.

[@10tenman10]

Why the fiberglass insulation and not 2 layers of the rigid insulation?

[@marykfcjane]

I have the same question, I’ve heard there are issues that arise over time with batts that are touching the concrete.

[@imthebestnotu]

Can I use dow THERMAX™ SHEATHING to pass fire hazard and use enerfoam to lock it in? I don't like the orange color of great stuff.

[@HouseImprovements]

yes you can

[@thedyslexic9936]

Instead of pushing insulation into the gaps above the foundation, why would you not spray foam the gaps above the foundation wall to stop cold drafts from hitting the bottom of the sub floor (in my area it gets to -40 pre-wind) and making the upstairs floor colder along the wall, as well as keeping insects out of the rim joist area...and then put the styrofoam and/or batts as you have done and then seal as you have done with spray?

[@merlin3921]

Should I seal the top plate to the concrete wall with foam - the orange spray in foam?

[@HouseImprovements]

yes, it helps

[@billmorley3530]

By installing the fiberglass batting first, it is not sealed against the warm outside air, which will eventually cause black mold and rotting of the joists. I think it would eliminate this problem if you apply the rigid form, first, seal it, and then add the fiberglass batting if you want more r value. Does that make sense?

[@christopherpavlicas]

Exactly!

[@scaldinghotcoffee3206]

Hello Shannon. You may have answered this already, but are you at all concerned with moisture wicking up the concrete foundation and into the wooden sill? Id like to do the insulation you've shown here, but my home's construction is older-1955-and there is no capillary break between the concrete wall and the sill plate. I've been told sealing the rim joists will cause structural rot. Do you have any suggestions? I live in climate zone 5.

[@HouseImprovements]

I have never seen one rotted. In my area we must seal this area to meet code. I'm in Saskatchewan Canada.

[@scaldinghotcoffee3206]

HouseImprovements Ok. Thanks for all your help!

[@phishertube]

I agree with scaldinghotcoffee on this one i purchased a house and it has a rotted rim joist from foam board sealing in moisture, i am building a extra house as we speak on the same property and i plan on using rockwool instead of fiberglass with no foam board so it can breath to fill those joists in the basement.

[@remingtonjohn4727]

At 8:01, you mentioned that you would put 2" rigid foam board in the box end joists and then put Rockwool R14 insulation in front of that... When you put in your 2" rigid foam board into the cavity, would you still need to put the spray foam all around the rigid foam? Or would the Rockwool insulation be enough to prevent any moisture or air gaps? Awesome videos by the way... Thanks for sharing

[@HouseImprovements]

Yes seal the gaps around the foam

[@Carolineinthecountry]

My house was built in 1926 and it has only a few "holes" that look like this. Is there something else I can do to insulate after filling the few holes with rigid & spray foam as you show in these videos? There is no wood showing...just concrete. I can share a few photos.

[@HouseImprovements]

Please use my forum. www.house-improvements.com/forums/

[@ThatOneGuyRichie]

Looks like there's a penetration in joists that is allowing air to flow through the insulation and turn it black on the end.

[@chrisbadger4089]

Can the spray foam and foam board be against a hot/warm duct or pipe?

[@teamusa4472]

Yes

[@brandonbailey4491]

So why use R10 rigid board? is R5 not enough?

[@chado1231]

if I use Roxul insulation and fill the rim joist to the sill plate can i leave it exposed and not have a vapor barrier?

[@HouseImprovements]

Roxul will not stop air or vapour movement on its own

[@spookerr]

What about future termite inspections???

[@jdvanallen2907]

Our area (including his if I remember correctly) doesn't really have that issue so it's not a major concern.

[@heyderekp]

I have some rim joists that are almost inaccessible due to wiring and other objects. I’m in climate zone 5 (northern, NY near Lake Ontario). In accessible joists I’m doing 2” rigid foam sealed with spray from up against rim joist. For areas I can’t access to get rigid foam into, would the best solution be sealing the rim joist perimeter with spray foam then using an R30 insulation to help with those spots? If so, should I used unfaced or faced?

[@HouseImprovements]

I would use faced.

[@heyderekp]

Thank you!

[@RajneeshKhanna]

Hi Shannon, thanks for sharing the video. One question, can i use Kraft faced batt available in Home Depot? And, which side should the paper face towards the exterior or towards the rigid foam? Thanks.

[@ronh9384]

Don’t use Kraft faced batts!

[@imthebestnotu]

Can I just fill the whole rim joist with rigid foam instead of using batt?

[@HouseImprovements]

sure if you want to

[@loktom4068]

Anything is better than 0.

[@DavidRodriguez-td7gz]

can this be done in a garage that's heated,

[@HouseImprovements]

+David Rodriguez Sure , you normally would not have end joists like this unless you have a floor over top.

[@skyline5354]

What’s the aprox price difference to do rigid foam boards vs spray foam ?

[@HouseImprovements]

In my area its about twice as much for 2" of pro applied sprayfoam compared to 2" of rigid. And about 50% more for the DIY sprayfoam compared to rigid.

[@adammiller5526]

Why do you not need to seal the flooring for the upper level? Could warm air not come from the floor above, especially around the air duct?

[@HouseImprovements]

Not sure I understand what you are saying? Please come to my forum and we can chat. www.house-improvements.com/forums/

[@huejanus5505]

I think he’s asking if warm air from the hvac ducts can leak into the colder area behind the rigid insulation and cause condensation.

[@shoes121255]

Any issue using foil faced foam in this area?

[@HouseImprovements]

no

[@csimet]

I just did my rim... while building my basement shop. I removed the original less than adequate install from when the house was built (1970s). Biggest tip I have... fit & install all your insulation first, then go back and spray foam the edges in one pass. The stuff is messy if you leave the can sit and drip between each cavity. ;)

[@rickdias7170]

Hi Shannon. I have a basement with the joists embedded into the concrete. I've read on a lot of forums not to insulate the joist cavity, as it would be prone to joist rot. Its better to pay the hydro bill than to repair the joists. I'm up in Canada. -30 winters. +30 summers. Just wondering what your take would be on this. Thanks in advance! Love your videos !

[@Matt_bryan]

Wondering what you decided with Rick I have the same issue with my place

[@rickdias7170]

@@Matt_bryan I found a few topics on Shannon's forums regarding this. I have a gap of about an 1" between the concrete and the floor above. I removed all of the packed fiberglass insulation that was packed in there and filled it with spray foam. I caulked around all of the joists where they meet the concrete. I sheeted my entire basement with 1" EPS, including between the joists up to the sub floor. Framed my walls. Added R14 roxul between the studs and the rim joists, and covered everything with 6 mil poly. I spoke to a few spray foaming guys in the city and they say they cover those all the time. I'd say in a more humid climate I would've maybe left them open to breathe, but its pretty dry here, and the basement was previously finished(horribly done). But everything was insulated before and I have absolutely no signs of any rot on my joists. My floor upstairs doesn't seem any colder than what it was previously either. There's so much talk on the internet regarding this, I didn't know what to believe. I think it'll be fine the way I did it tho. I made sure the vapor barrier in those joist cavities are all nicely sealed with acoustica seal. Plus the a/c and and a dehumidifier pulls out alot of the moisture in the summer

[@Matt_bryan]

@@rickdias7170 wow awesome Rick thanks for the reply been trying to figure out what to do for the longest time now... may I ask where you live just to see if we have similar climates, im from southern Ontario

[@rickdias7170]

P.S. the house was build in 1953. The basement was finished in 1994 according to the date I found on the drywall. Almost 20 years of having those concrete joist cavities covered with no sign of rot.

[@Matt_bryan]

@@rickdias7170 perfect ours was built in 1959 thanks for all the help

[@stevecash7174]

Does insulation still work when you put new insulation over the old one?

[@HouseImprovements]

yes if the old stuff is in good condition and your not packing it in.

[@bhadz100]

Is it better to do batt first then foam board or vice versa

[@HouseImprovements]

Some prefer the foam first and then batts .

[@markc4166]

Caulk or foam boot to the subfloor. Mastic duct seal duct before covering it & stop belly from jiggling when shaking foam.

[@dice8245]

I Shannon, If my wall on main floor is r20 value. Can i go higher on my basement like r12 rigid + r20 batt insulation for my basement wall? Thank you

[@HouseImprovements]

for sure.

[@dice8245]

Thank you so much 🙏

[@beebob1279]

My understanding about using the the rigid foam is that it's supposed to be against the wall and the batt insulation is to the inside of the room. The reason is because you set up traps moisture and causes worse problems such as moisture and mold.

[@HouseImprovements]

If you sealed the joints under the sills and rim joists you may. If you did not that air movement will help dry the void and the rigid foam contains that air movement to those spaces.

[@christopherpavlicas]

I put the foam board in first, tight up against the bond. Seal the edges with spray foam to eliminate any drafts and then add bat insulation for extra R value.

[@markmayfield4210]

Our code states the R value has to be R 20. What combo of bat and board would you use to achieve that value?

[@HouseImprovements]

depends what you are using. If you have 2 layers of R12 batt insulation you are already at that point. in our video we did 1/2 piece of R20 and 2" foam ,so that was R10 plus R10.

[@deerhunter7482]

Great job but don't use foam without glasses .

[@gamerclownz2783]

is that how this foamspray looks on video? I have always used this foam spray and it was yellow color? or am I buying the wrong one? looks like I have the same can as you.

[@HouseImprovements]

could be different brand. There are orange, yellow,white and blue sprays that I have seen.

[@thedyslexic9936]

same shoot, different color/colour

[@curtisbme]

That can is Great Stuff foam "Fireblock", which is orange. You use this when you are dealing with penetrations through floors or other areas where you need to use fire blocking of some sort as it has some fire rating. Their standard stuff is yellow as is their low expanding foam (then they have a greyish 'Pest Block"). Other brands of foam can have different colors.

[@DONALD1951]

Great stuff foam is not great. Makes a mess

[@DONALD1951]

I put the foam board first then fiberglass or roxul

[@freetolook3727]

Code says you can't expose the Styrofoam insulation but what about the exposed wood floor joists and flooring?

[@rckoegel]

The 'can't be exposed' bit is to protect people from fumes when the foam burns, cause it will burn fast and easy and is poisonous. It's not 'just' to protect it from burning. Not sure it applies in crawlspaces, but in does in garages and living spaces. I haven't, yet, seen anything online that says rigid foam insulation on rim joists in crawlspaces / unfinished basements needs to be covered. Haven't exactly checked codes though either.

[@chikoperiko9]

Wouldn't you want the foam against the rim joist first and the use bat insulation after .. just for moisture not to be trapped in behind... im just wondering ..

[@35057]

Well it looks like I’ve gotta redo all my joist insulation I just did then. 😖 my house hangs over the foundation so I’ve been working at that.

[@HouseImprovements]

There is more than 1 way to insulate joist ends, you may be fine. If you used batt insulation only, be sure you used a air/vapour barrier afterwards if its required in your area. You can use our forum if you have more questions.www.house-improvements.com/forums/

[@DaveLarose3]

Any particular reason that you used fire-rated foam here..?

[@HouseImprovements]

Actually this type was not fire rated.

[@oby-1607]

There is no such thing as fire rated foam insulation. The orange color is there for an inspector to see the air leaks have been sealed up. Usually between floors as air leaks will hasten fire transfer. But foam is foam and cannot be fire rated.

[@krysm2022]

Seems like a great way to encourage mold growth...?

[@runningwolf8115]

his it better to install the rigid foam first then the insulation batt

[@jasonwilkins1969]

That's what I was thinking. Install Fiberglass batting only where a vapor barrier can be established between the outside and conditioned space (install rigid foam with spray foam sealing the edges)

[@mpxz999]

HOLY SHIT. THIS IS MY EXACT SITUATION We even have the same window! 1970s Canadian homes are so weird Thanks for this!!

[@gonzalorengifo1031]

Shouldn't you put the XPS first and then fiberglass? My understanding is that fiberglass insulation cannot be in direct contact with concrete wall. If you replace fibreglass with mineral wool you could then do as your video

[@danielmadrid8582]

Is it possible to over insulate the rim joists? ie too high of a R value

[@gilberthardware7619]

Not possible. What is possible is getting a house too tight which would be doing everything, which I do but I install make-up air to allow fresh air to come into my cold air return to replace air spent outside by exhaust fans and the hot water tank.

[@pussylipshiz]

If you have moisture in the board, it will not be able to dry out, and mold and rot could start, I think the only way to do what hes doing is to have zero moisture in the walls?

[@davidhsieh2761]

Not if it's sitting on a sil plate, for fully cast-in/embedded joist in the foundation wall, NRCAN recommends no more than R5...

[@acreguy3156]

Great demo, thanks! Can you use acoustic caulking instead of spray foam to deal around the 2" foam board? I don't see why not, unless the foam is more permanent. I look forward to the day they invent a spray foam that can be delivered with the can in *any* orientation!! In many cases, it's like threading a needle with a sledge hammer or watching a pig on stilts.

[@HouseImprovements]

I think you can ? I dont think the acoustical will eat the foam. I have used short (12" -24") clear hose on the sprayfaom straws to extend them and it works pretty well.

[@acreguy3156]

@@HouseImprovements Good stuff, Shannon. Thanks!

[@kakabekadigger2851]

Hey Shannon. Love your videos. We’re you using low expansion foam or regular. Thanks

[@HouseImprovements]

This is regular foam.

[@brettpauley4898]

Is the batt insulation necessary?

[@HouseImprovements]

gains more R value

[@DEgan5660]

hilti spray foam gun makes spray foaming way easier.

[@dondonaldson1684]

To your last point, poly-iso is fire rated and would be installed with the foil side in.

[@HouseImprovements]

If you use a fire block foam to seal it.

[@imakeituptoyou]

Why wouldn’t you use the foam board first then the fiberglass?

[@mightymikee1]

Are you using fire retardant spray foam? Its orange thats why im asking

[@VinceM797]

What's the name and brand of knife?

[@HouseImprovements]

Olfa

[@VinceM797]

@@HouseImprovements thanks!

[@banyai420]

I am currently doing the same thing, EXCEPT, I’m putting the rigid foam directly on the joist, sealing around with spray foam, and then the batting. Seeing as I’m located in MN the vapor barrier(2”rigid foam) should be right against the joist.

[@percyfaith11]

The vapor barrier should be the closest thing to the inside. If you put the rigid foam, then the batting there is a chance that condensation will form on the foam.

[@banyai420]

@@percyfaith11 that’s a big negative, at least in MN. Your vapor barrier needs to be directly against the joist. If you put batting and then a vaper barrier you are creating a hot spot for mold.

[@banyai420]

@@percyfaith11 the foam is waterproof, hence vapor barrier. Batting insulation cannot get wet

[@percyfaith11]

@@banyai420 Think about it Brandon. A vapor barrier means vapor can't pass by. If water vapor can't pass by and get to the joist or the batts how is mold going to form? If you put the vapor barrier and then the batting the moisture will condense on the vapor barrier because the batting has allowed the foam to cool to the dewpoint. ALWAYS have the vapor barrier be on the warm side of any insulation.

[@banyai420]

@@percyfaith11 simply look up the building code bud

[@brockbaker3able]

Proper method is to put the foam in first. Seal it complete so you have your vapor barrier then place the batt on the outside. Flash and batt

[@HouseImprovements]

I have a video for that method as well.

[@nancyorkeithm1518]

When you touch the pink insulation without gloves I cringe 😬 then I laugh at myself bc you handle The spray foam like a pro. I Used it for The first Time a few months ago and ended up with it in my hair for About 6 weeks :)))) I’m a woman so I kept coloring the foam in my hair With a marker until i Could FINALLY work it out !

[@HouseImprovements]

Well if you ever seen me without my hat you would know I could not get much in my hair ! LOL #follicallychallenged