Community: Building Code Questions

Q & A Instructions

[Click map to enlarge]

The web site has a wealth of articles on a wide variety of construction topics. Before posting your question, you may want to check out the articles on this page: How To Do Everything. You just might discover an article there that provides the information you seek.

Please register for a free account or sign in to ask and answer green building questions.

If you want to post a question, the usual rules of courtesy apply:
1. Be nice.
2. If you can't be nice, be polite.
3. If you can't be nice or polite — well, please be brief.

To attach a photo or illustration: Under the box labeled “More explanation,” look for the words “File attachments.” Click that, and you should be able to attach a photo.

Thanks for joining the conversation!

1 Answer

Is there a code requirement for residential boiler piping insulation?

Is there a code requirement for residential boiler piping insulation?

If so, what is the R-value for pipes in conditioned space? And unconditioned space?

We live near Baltimore, MD.

Asked By Brantley Gent | Apr 30 16
6 Answers

Ridge Vents - see light?

I was at our new construction home yesterday. It is not yet insulated. I looked up and noticed one small hole where light was coming through. It was at the peak of the roof (runs along the length of the house - it is a ranch). The was no plywood in this area - just synthetic tar paper/shingles could be seen. Our builder said this just where the shingles come together and that no water or anything can get in there. If they put plywood under it, it will wick and rot. He said he could put steel wool there or caulk it but that is not normally what is done. It is normally just left open to vent.

Asked By Carolyn Farrow | Apr 22 16
12 Answers

Addition cement foundation below grade, patio pour?

Hi all,

We just moved in to a home about a year ago so I am still in the process of finding things out (and learning what's terrible and what's not...), but I had a question regarding pouring a patio at grade if the cement block of our foundation is below grade.

Picture attached.

The blue metal is what I assume to be flashing to cover the treated wood from the elements, but you need to go down about 2-3 more inches to reach the end of it where the cement block begins.

Asked By Ryan Lambert | Mar 20 16
7 Answers

Poly and Canadian building codes

This comes up quite frequently and I thought it might be useful to lay out what is actually required by the code. My description relies on the BC Building Code, but I am fairly confident it applies to all provinces that have based their codes on the NBC.

The code requires all building assemblies to include an air barrier and a vapour barrier.

The air barrier can consist of a variety of sheet or panels materials. It can be located anywhere in the assembly. That is the inner, intermediate or outside surfaces of the assembly (

Asked By Malcolm Taylor | Apr 4 16
8 Answers

Vapour barrier for above-grade walls and ceiling in Canada?

So I've read a bunch of Q & A on the vapour barrier and how it's not necessary for certain climates, but if we are stepping out our insulation above the dew points on our colder climate (Pickering, ON), would it hurt to have the vapour barrier?

Asked By Reginald Chin | Mar 29 16
8 Answers

Basement insulation...pull the XPS?

Long story short, between work and family obligations I've been busting my tail to get my basement walls insulated and studded in preparation for finishing it off. Had an inspector come through only to hear that he considers the 2" xps I installed behind the stud walls to be a prohibited vapor barrier. Mind you I took extra caution to put in nice tight seams, tape the seams with that special red foam tape, and caulk around the perimeters AND I put up and secured the stud walls in front of the xps.

Asked By Will Golden | Mar 25 16
2 Answers

Certification for re-purposed polyiso. Manufacturer is unkown

The Farifax County code in which I live is as follows:

N1101.12.1 (R303.1.1) Building thermal envelope insulation.

Asked By frost patrick | Mar 24 16
8 Answers

Advice for insulating a new build unfinished basement?

We are planning on tearing down and rebuilding our home which will be a 4500 sq ft bungalow with an attached quad garage. Finishing the basement is not possible immediately, so what is the best choice to economically insulate the basement walls without having to drywall up? Would thick rigid foam be the only option to get R20? Is it allowed to just put up rigid foam with nothing else on the foundation wall?

Asked By Reginald Chin | Mar 22 16
1 Answer

I have a question about insulating the attic space in an addition

I am planning a 360 square foot addition with a 12 x 12 gable roof so there will be a large attic space. The ceiling will be 2 x 12 joists to allow for a clear space in the room below. I will put r-38 fiberglas between the ceiling joists to meet code. My question is if I later choose to insulate the roof rafters later on can I leave the insulation in the ceiling?

Asked By Bruce Sukennik | Mar 15 16
3 Answers

Sub-slab insulation under a bearing wall?

There was a previous post very similar to my situation posted back in 2012....I am looking for any new or additional clarification on this question. I have two interior 2x6 bearing walls, 30' long which my engineer says must be able to support 700 lbs per foot. He requested a footer with the slab turned down to sit directly on the top of that footer. I would prefer to run my 2" thick EPS insulation... rated at 40psi....continuously across the whole bed of 4" crushed stone which would also run across the top of the footing.

Asked By Jonathan Scholl | Mar 14 16
Register for a free account and join the conversation

Get a free account and join the conversation!
Become a GBA PRO!