Crawlspace insulation – wraparound porch
whardy7
| Posted in Energy, Heating & Insulation on
I have a 3′ tall crawlspace with 14″ joists. It is surrounded on all sides with a 10′ porch full of sand (concrete stemwall and porch floor). I put four 10′ long 8″ ducts for vents on all four sides of the house (16 total) that can be open or closed.
Do I still need to do some kind of insulation on the inside of the crawlspace?
Replies
nope
Spheramid Enterprises Architectural Woodworks
Remember when it was you doing that.
I think you should consider the climate you live in. Will the space gets colder then 45F in the winter? Did you install a vent pipe for the ground gasses to escape? Are you in a radon gas area? If you cement the crawls space floor then i agree you wont need to insulate. BUT you might want to ask your hvac contractor about making it conditioned air space to control ground moister. Also consider the leaking that goes on in duct work. Will it pressurize the crawlspace area?
if you are in a cold climate... you can either insulate the floor... or insulate the crawlspace walls..
i prefer to insulate the crawlspace walls and make the crawl into a part of the conditioned space..
your type of heating and cooling will also influence your decision..
short answer: it depends... so... where is the house located ?
to insulate the crawlspace walls ... where is the house located
That's got me head scratching just now. It sounds like the porches have sand fill from their stemwalls, back up against the perimeter foundation wall. So, they may actually be insulated, with 10' of sand.
Profile says Stillwater OK.
Building Science says that's Mixed-Humid, and recommends a conditioned c/s.
With those prominate dormers, and the advanced state of construction, I'm thinking that the recommendation would be to seal up the c/s, & foam the roof deck. Run the hvac returns in the c/s and the supplies in the attic. That would keep all the ductwork & equipment in some sort of controlled space.
My only concern would be how the perimeter foundation/porch deck/floor deck joint is handled. If I've "got it" right, that is.Occupational hazard of my occupation not being around (sorry Bubba)
A couple of questions, then.
1)Conditioned crawspace that is sealed - should I plug up the 8" tube vents going through the porch floor? Is that literally what we are talking about being sealed and conditioned?
2)What do you mean about the "deck joint"? If I can understand what you mean by that, I can explain how I did it.
It seems to me that the crawspace is as sealed as any could be (excepting the vents I put in) because of the 10' of sand and concrete. But, I am not sure if I should put something on the inside of the stem walls - a coating or some insulating board. Seems that would be redundant.
1)Conditioned crawspace that is sealed - should I plug up the 8" tube vents going through the porch floor? Is that literally what we are talking about being sealed and conditioned?
Yes. Could remove the vents, too. Some of the reasons for venting a c/s involve ground gasses, but mostly, venting for the c/s is to give an easier path for moist warm air to flow out of the c/s instead of up through the floor structure. Building Science (rightly, IMO) is 'against' any scheme that allows moisture-laden air to build up anywhere it might later condense.
2)What do you mean about the "deck joint"? If I can understand what you mean by that, I can explain how I did it.
The joint where the house foundation translates into the floor & wall structure and where the wrap-around deck terminates against that structure. There's a number of way to detail that, from a wider ledge on the foundation beam, to mirror the porch's stemwalls, to a rim joist for the deck against the house's rim joist. When you said sand, my brian starting trying to kick back which way a termite shield would go in, which then got me to wondering about the deck v. house flashing.
It seems to me that the crawspace is as sealed as any could be (excepting the vents I put in) because of the 10' of sand and concrete. But, I am not sure if I should put something on the inside of the stem walls
More sealed, in some ways. I want to say that a foot of earth is like R20, so, you have a lot of thermal mass agains the c/s walls. I probably would have waterproofed the house's foundation wall before backfilling with sand, but I'm belt and suspenders that way. You may need some insulation where the sand fill "is not," usually with a bit of overlap to prevent bridging.Occupational hazard of my occupation not being around (sorry Bubba)