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5 Answers

Sizing an HRV

I am working on sizing an HRV for my son's house. Using ASRAE 62.2 I get 77cfm. Using ACHnatural of .35/hour I get 144 cfm. Using Venmar's tables I get 160/80 cfm for the high/ low. Using 10 cfm/room and 20cfm for master bedroom and basement I get 180 cfm. I wonder if some of the higher numbers from the manufacturers are trying to account for high speed venting of bathrooms. However I wonder even at 180 cfm with ten supply and return grilles if he HRV can pull enough air out of one bathroom to stay ahead of a long hot shower on a cold winter's night.

In Mechanicals | Asked By Steve Kent | Jan 13 13
1 Answer

Internal Insulation of Masonry Walls

I am renovating an Brick Home in Toronto. The exterior walls are Load bearing brick walls with some parging, furring, and plaster board. I want to add insulation on the interior using the wall assembly described on page 24 of the pdf guide "Internal Insulation of Masonry Walls: Final Measure Guideline" see below for URL. I have a question about this assembly... I noticed that there is no vapour retarder, should I install a vapour retarder on the warm side of the insulation between the insulation and the wood studs?

In Green building techniques | Asked By david lam | Jan 14 13
2 Answers

ERV ducting - how to insulate?

We have an ERV, which works great for our house, which is in a cold climate (i.e. this week will be below zero at night for the next four days, and teens during the day). This is our second winter in the new house. We have discovered that due to location, a hot water line (PEX with R-4 insulation) crosses over the ERV incoming duct in the between-floor truss level. It has frozen at this point.

In Mechanicals | Asked By Richard and Miranda Menzies | Jan 12 13
6 Answers

Insulating a scissor truss

When insulating an unvented scissor truss roof with loose cellulose, ~24" heel height and ~ r-30 spray foam against the underside of the roof decking, can I leave an increasing airspace as I work my way up to the peak? In other words, I want a consistent thickness of cellulose (~18") starting from the raised heel up to the ridge. Can the remaining space between the cellulose and spray foam be a air space or am I risking condensation somewhere in the sandwich? This is assuming air barriers at the roof decking level and bottom chord. BTW: Zone 7-8. Thanks.

In Green building techniques | Asked By Matthew Michaud | Jan 12 13
1 Answer

HVAC Design - Central Jersey

I"m looking to hire someone who is knowledgeable about building science to work with me as a consultant on the design (and possibly installation) of an HVAC system for my home remodel in central New Jersey. Can you recommend someone? Thank you. Deidre

In Mechanicals | Asked By Deidre B | Jan 12 13
3 Answers

Floor joists and insulation for vented crawlspace in a flood plain

This is a rehab of a home in a FEMA floodplain in a suburban area. The house has never flooded and is not likely too. In any case, the county will not allow land disturbance of the existing foundation and we cannot enclose the crawlspace because of the floodplain. However it appears many of the floor joists are warped so we may need to replace the first floor deck and joist system.


In Energy efficiency and durability | Asked By Patricia Shields | Jan 6 13
2 Answers

Rigid foam board in Newfoundland

I live just outside St. Johns Newfoundland and will be building a new house this coming spring. I will be using 2x6 for framing. In the cavities I will install Roxul R -24. ½ spruce plywood covered by building wrap. Next I plan on installing 2 inches of Owens Corning ridged foam, tape seams. Next 1x4 strapping, rainscreen on 16 centers for attaching 6 inch spruce clapboard. My question is 2 inches enough to keep the wall warm where I live. Average winter temperature is 0C but it can get colder. Also can be quite damp with horizontal rain due to high winds.

In Energy efficiency and durability | Asked By paul fowler | Jan 12 13
5 Answers

HRV layout and minisplit location

i was hoping i could get some advice on where to locate hrv diffusers and both the interior and exterior units of a ductless mini-split air source heat pump. i hope to attach a drawing to this post. the kitchen wall faces due south and the main entrance and driveway are to the north. the house is a new build, a little over 600 sq', and measures roughly 22'x28'. the design temperature is -32 celsius and the mini-split would be facilitated by electric baseboards. thanks!

In General questions | Asked By erik olofsson | Jan 10 13
16 Answers

Can a cottage built on a concrete piers ever be as warm in Canada as one with a full foundation?

I am trying to minimize the use of concrete in the design of a cottage on flat sandy-ish soil near Huntsville, Ontario. I have heard from contractors that a cottage on piers will always be drafty and that I should go for a full 4 ft insulated concrete perimeter foundation (crawl space).

My question is this - in reality (not theoretically) - can I insulate the floor of a building built on piers enough that it could match the full foundation? What would it take?

In Energy efficiency and durability | Asked By sarah okeefe | Jan 5 13
0 Answers

Vented cathedral ceiling with foam board below rafters for air seal & insulation.

Hi all, I am building a log kit type home in the hill country of Tx (west of SA). This is a dry area I believe designated zone 3. This is a small (600+sqft)home. I will have one section as a great room with vaulted ceilings. I intend to ventilate that ceiling w/ 1" air channel using foam board. I will then use fiberglass batts between the 10" rafters and ridged foam boards (edge taped) below the rafters to air seal the ceiling then have pine T&G as the finished ceiling. I believe I have read that you need a flame resistant layer over foam board.

In Energy efficiency and durability | Asked By RJ Stalzer | Jan 12 13
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