AIRTIGHT MUDSILL FRAMING DETAILS

Let's take a look at a critical potential air leakage location in the rough frame.

[@josephmerritt1411]

Steve, thanks for your videos. They are very helpful, especially for me, a DIY homeowner building his house. Your explanations are outstanding. For the sill plate, I chose to use a Conservation Technology (Baltimore, MD) BG75 sill gasket (for 2x6), which is cellular EPDM rubber material with two bulbs that compress (equivalent to your comment about two beads of caulk) along with a similar EPDM BG72 gasket under the RIM boards. The material is more expensive (6-8x) than the standard Corning sill sealer. Still, they will last much longer, seal greater gaps, and do not crack like caulk will over time, and because you don't need to apply two beads of acoustical sealant, I saved time and cost of manual labor and material cost of Tremco Acoustical sealant. Both systems will work. BTW, we cut off the bulbs 4 inches back at the interface between two adjoining pieces and overlapped the flat EPDM.

[@littlemanwithglasses5491]

You have no idea how much I love this detail

[@stevendobson9626]

Good info. Do you need to seal between the two bottom plates or where the bottom plates boards butt up to each other? How do you seal the Zip sheathing to the bottom plates/foundation wall for continuity?

[@chrismarfia9917]

You should use the Protector Wrap triple seal sill sealer.

[@kpezzolesi]

Great video Steve. Regarding the mudsill, do you prefer extending out the mudsill under the R Sheathing or using 2x blocking? I've noticed you've done it both ways.

[@danielmcneely1579]

Dammit! I was just going to ask the very same question to see if it would be more efficient/cheaper to use a 2x8 as the bottom plate

[@kpezzolesi]

Great detail Steve. Quick question: Since you have a double mudsill and you overlap the joints, do you have to install anchor bolts at both top and bottom joints?

[@Cpt_Guirk]

I like your singing. It helps me retain the information. Also curious about the double sill. What's the reasoning for 2?

[@boydkramer]

Pretty sure you flipped the location of the sealant in your drawing from what is show at the beginning of the video - sealant on top of sill seal towards interior and sealant below the sill seal towards the exterior. You show the opposite on your drawing. Which do you recommend?

[@francoisbouvier7861]

You were recently in Vancouver. The guys at BCIT have some very interesting details relating to this subject.

[@davidbruce5377]

I put a backer rod on the sill foam around the entire perimeter and tape off the exterior transition.

[@nobleroofinggeneralcontrac7961]

Brilliant detail!

[@tamil1001]

Steve, For a belt and suspenders approach how do you feel about taping that joint with a good tape like Siga fentrim in addition to the detail you described?

[@markdusseau5100]

Steve when you zoom in the sill plate around 2:45 it looks like the caulk is not adhering to the surface.

[@hu5tle-]

I like the detail and used it on my first build, but am debating ease of install and cost vs. just taping the whole outside with Siga Fentrim. Much easier to convey, "tape the seam vs. teaching a multi-step process, especially if its not your team.

[@jonathansage2147]

I went the route of rubber gaskets and liquid flashing the exterior for this exact reason. It's a good detail, but it's only as good as the guy doing the work.

[@LuminairPrime]

@ansage2147 It's a good point that you can inspect and verify the sill flashing that is stuck to the exterior, but you can't ever see what's under the plate!!

[@escortracer]

I would like to know why you stop the sealing at that plate? Why not continue up at each contact point. Concrete to plate, plate to plate, plate to band joist, band joist to deck, and deck to bottom plate of wall?

[@jonathansage2147]

Because your sheathing takes over the role of air barrier past that point.

[@aldoogie824]

What’s behind the black curtain steve!!

[@Solidbuilthomes]

What's the benefit of a double bottom plate?

[@ArthurDentZaphodBeeb]

Contega HF is expensive to use as the sill sealant. In my tests, Green Glue Compound (not Green Glue Sealant) works better, is half the cost, and more readily available. Contega hardens and shrinks quite a bit more than Green Glue Compound. Don't think it's a good choice for sill sealing.

[@LuminairPrime]

Tape is stronger in some attributes than liquid sealant. I wonder if there's any reason to NOT use flashing tape along the mudsill, because one path around the whole house has gotta be only a few hundred bucks of tape plus the effort to clean the sill and roll it down. I guess the assumption is that the way they're doing it here with foam and sealant is already more than enough.

[@elbuggo]

I any case, you need a vapor barrier between the concrete and the wood.

[@jimr4566]

tape or liquid flash the sill plate to concrete wall

[@Krunch2020]

You still have to tape or caulk the bottom of the sheathing to prevent failure. Edit: Exposed edges of OSB will expand and pull the shear nails through the surface rendering them useless.

[@stevenbaczekarchitect9431]

The bottom mudsill usually extends out to solve for it

[@Krunch2020]

👍 just another item amongst the million! Also, houses do move upwards in California. 😂 they discovered a “vertical component “ in the 1989 earthquake. It was about 3’. 😮

[@tysleight]

​@@Krunch2020 that was before many of us were born.

[@baxt1412]

Really wish I could retrofit my 1918 house with sill sealer

[@traviswilliamson842]

All laminations should be sealed with caulk or an elastomer. Kings jacks top and bottom plates.

[@MitchOfCanada]

i have seen countless walls drop/crack move away from the wall assembly which is held together in place with OSB. Acting as a cantilever at the front of the house Over 3/4" Gaps happen on the back plate as in alberta they are not lagging/anchoring to the concrete, just naling to the 2x4s embeded into the concrete wall. Moreso bad on walkouts. But winter digs, no compaction of virgin ground results in foundations moving up and down all the time. then once the weight of the house is actually there, drywall/roof. the ground starts to setting a bit and the pads. Its just bonkers what they are building these days.

[@elbuggo]

Sounds awful!

[@tysleight]

Tremco acoustic sealant is next to impossible to find.

[@jonathansage2147]

Fun. Seems like a theme for most products the build show recommends. Try to find 4" thick rockwool comfortboard. I'll wait.

[@tysleight]

@@jonathansage2147 no kidding!

[@davidsmith-be7rw]

Anyways is not a word. Grammatically incorrect and slang, sounds and is not acceptable. The correct way to say the word you use so often is anyway. For what it's worth. Not anyways. Thanks for all the other info.

[@stevenbaczekarchitect9431]

Great thanks

[@baxt1412]

Goodness move on

[@mycowboyways915]

Anyways...Thanks for being you. Don't change a thing. Love the Channel !