Parapet Walls - Are They A Good Idea?

Roger looks at the pros and cons of parapet walls.
Check out the Steve Roofer channel and London Flat Roofing.
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londonflatroofing.co.uk
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#ParapetWalls #FlatRoof #Roofing
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[@American-In-Mykolaiv]

Great explanation of "thermal siphoning" - most of the houses here in Ukraine have no insulation, so the little house we bought got an upgrade - first the ceilings got two layers of rock wool, about 30cm, then the sides of the house were covered with 10cm foam and stucco, then I extended the roof by one meter all the way around, so I could wrap the corners with foam and cover it with under roof rock-wool. There are no cold spots, therefore no condensation. For winter windows I added a third layer of clear plexiglass with wooden frame to the outside of the double glazed windows. Little condensation around the glass edges in the kitchen and bathroom. Sure keeps from sending gas money to Putin. Love to watch your videos, you get to the point without much ado and tell it like it is. Thought about heat pumps, watched your videos and will hold off. Best investment were some solar panels, a low frequency inverter (6KW) along with 800AH LiFePo batteries - reduces my utility bill by half, except for winter months. Thanks for your videos!

[@MadRat70]

It sounds like you are focusing on brick-faced wall problems in general. You just happen to make the topic about parapets. Your topic has nothing to do with the roof. Honestly, most parapets in the states are over 8" block. Your perimeter to hold down your roofing typically ties into wood fastened to the backside of the wall so that counter-flashing covers your termination bar. So your roofing is never attached to the coping. Sometimes coping metal will cover the term bar, but it typically is used over wood caps, not stone. With metal coping (aka cap metal) you fasten front to back using anchoring under the face metal, referred to as clip metal or cleat. Unless you have a smooth face for the clip metal, you are going to have air penetration. And only really in that situation would it be a roofing problem. Otherwise by definition, coping stone is an engineering problem. Coping stone has a roofing function, but the engineer has to sign off on any changes to it because it is a structural component, tied to weight-bearing on the wall. No roofer is taking on that responsibility.

[@sonandmoon2958]

Deuteronomy 22:8 When you build a new house, make a parapet around your roof so that you may not bring the guilt of bloodshed on your house if someone falls from the roof

[@dryfixpreservation]

Terrible advice here Rodger. How do you propose to tie In your cavity tray at the head of the wall to the inner timber frame wall? Also what stops condensate forming in the cavity above roof level and decaying the timber frame? Where is the timber frame gaining its stability especially if its taller than 300mm? How do you ensure continuity between the cavity wall insulation and the roof insulation when constructing a warm roof design? A far better sution would be to stick with the traditional method of construction, build the parapet to NHBC guidance and simply use an insulated internal lining to remove the cold bridge. Come on skill builder I expected much better advice than this!

[@virginiabrown4281]

Our 30 year old house has a separate garage with parapet style roof, it's uninsulated but that hasn't stopped the ongoing problem of leaks. Parapet incorporated into roof design is bad because it's so easy to get a faulty, problematic result. We have just replaced the roof and now must find a carpenter that can address the parapet because as described in video the roofing isn't even the real problem. Even though we aren't dealing with insulation and condensation, addressing the coping stone or top of parapet in video was very helpful. I can only fantasize about ripping out roof and redesigning - I hate our parapet roof!

[@syncrosimon]

Makes sense👍👍

[@purplemonkeydishwasher5269]

Great vid again

[@ArtOfHealth]

I own a 125 yr ol commercial nearly low pitch flat roof. The city recently put 4 4x4' skylights. They worry me. I want the city to do something to prevent their seams in the skylights from leaking in to my building. We had a weird twister last week and 1/3 of my roof was ripped up. Flooded half my store. Angry.

[@franklinkarrass5830]

I knew nothing of parapet walls. Although I have seen them I never knew the nomenclature. You pointed out some very informative problems. Thank you. 👍👍

[@wheres_bears1378]

They look great but I would never do this if building a house, that water needs to get away from the house as fast as possible, traditional roof is best

[@JamesBrown-mt5ru]

Perfect timing! Roofer asked me today if I wanted to retain the parapets. He explained the situation exactly as the video. I now feel knowledgeable.

[@Tensquaremetreworkshop]

I have a couple of neighbours with the same story. First the roofer replaced the leading (sloping warm roof with parapet) then new coping, still condensation. Massive job to fix, so they have to live with it.1960s build, so originally it did not have heating. Cavity wall retro-fill. You have nailed the reason.

[@kevinrae3299]

Roger is correct about taking insulation up the parapet wall, I always make sure I take the membrane up , over and down 20mm . So as the roof is water tight without the cope/capping.

[@effervescence5664]

That's a clever way of solving the issue, similar to my old builders which follow Joe Lstiburek's building science "perfect wall". As long as the Water > Air > insulation barriers are all joined and layered in that order it minimizes and in most cases removes the issues.

[@lambjf187]

It needs the insulation standing up on the inside of the parapet wall and then the roof membrane covering extended up and under the Cap stone. Will require extra width on the cap stone to accommodate the increased depth of the parapet.

[@lazylad8544]

Great demo. Absolutely gem of a video. I wouldn't of learnt anything today without that video👍👍. Top man rodge.

[@kelstra1997]

I like your solution Roger and it's pretty much how a competent Architect/Designer would normally detail it. In Australia we don't have as many dampness condensation problems as you have in the UK due to our warmer climate - we certainly have them but not as often. Over here, concrete roofs are not all that common, we certainly have a few parapet walls but usually in conjunction with metal deck roofs. Before I retired I worked in the Architectural profession and I have detailed many parapets in my time. I am pleased to say however, that I can't think of a single instance where they gave a problem. I would say that trying to flash into the face of brickwork at a DPC is always fraught with danger and we always detailed our parapets with the roof flashing carried up for the full height of the parapet and over the top and almost always in conjunction with a stud frame as the inner part = exactly as you explained.

[@chaconjohnson]

Great video and explanation. I'm building my extension now and am debating going with a parapet vs not. The top will be a walk out balcony so I figured the parapet would act as a nice bit of privacy from neighbors. The points you make about straight walls and how they are great looking when they're first done but over time they begin to stain and other problems are created, I could not agree more, I see this all the time in Brooklyn. I do like the overhang roof because when it does pour you do feel a sense of relief knowing that the water isn't coming straight down as soon as you open the door or running down the wall. That sense of relief is reason enough to go with an overhang versus a parapet.

[@exushawkz1318]

I've really learned something today Rodger and will be using this if I take on an extension like this, keep up the great vids😁👍

[@jameshamilton6096]

Absolute Genius. Many thanks for that clear and concise explanation.