Preliminary home building technique questions…
Hello,
i’m considering building another house for my family (did one a couple years ago – my first) and being a loyal subscriber to FHB I enjoy reading many of the interesting articles regarding certain techniques. In particular, was the foam insulation underneath the cement slab in the basement. I cannot recall exaclty, but in a recent (i.e. < 6 mos) issue, there was a diagram which illustrated 4 layers of XPS rigid foam insulation. Around where i live (southern Ontario), this technique is never really used, so as I am asking around, people are looking at me funny when I talk about this. I think this is a great idea, and my main question is how does this affect the foundation process. In particular, foundation guys around here have concerns that the cement slab floor will be more susceptible to cracking if you do the foam. Typically around here there is just stone, then cement slab right on top. I think the XPS rigid foam is a great idea, just not a lot of information in my area about it. If anyone has pros / cons, approx. cost / ft2 installed (ball park anyways), that would be great.
My second question relates to drywall installation. A very highly regarded drywall contractor suggested on his own next house he wanted to glue the drywall to the interior walls and use less screws. He said this would help with drywall “pops” and screw heads showing, etc. This seems ok, but I have some reservations (since he was suggesting I do it in my next house) since wouldn’t you be relying on the paper of the drywall to hold up the entire piece of drywall, save except for a few screws???
Last question relates to siding. I was looking at a ranch style house and I am interested in fiber cement siding, but there is little information available in my area about installed cost. I know it’s very difficult to say, but can someone tell me what the approx. cost of this is in related to brick or vinyl siding. From what I’ve researched, it looks like it’s in between the two, but I wanted confirmation that this is an installed price. Takling to a few contractors around my area, they made it seem the fiber cement was actually more money installed compared to brick by the time you add everything up. Any feedback on this would be very appreciated. Also, if people could give their thoughts as to if they think the additional cost for fiber cement siding is worth it. I don’t live in an area where termites are an issue, i personally just like the look and longevity of fiber cement siding, but like I said, this is relatively new product in my area, so I was looking to get a bit more information.
As always, thanks in advance for your help!!!
Replies
Sometimes it's better to have 1 topic per thread...
Anyway...
basement Slab: you said: >> Typically around here there is just stone, then cement slab right on top. << Ontario? I'm shocked!! If the slab is built strong enough - ie thick enough, some wire and possibly some steel it will be fine with the foam. The idea is that you provide even support and the slab basically floats on to of the substraight. That is the way stone works too - even support. Expansion joints for Isolation at the edges and at any places where columns etc go through the slan to footers below is very important. BTW - foam comes in different compressive strengths, and naturally the cheap stuff has less load beariing capicity. Personally I woldn't want a house anywhere in Canada without foam under the slab - unless the house was free :-)
Drywall- nail pops occur most often at the edge of rooms on the ceilings. Some of this is caused by trusses moving around and nailing/screwing the ceiling too close to partitions (interior walls). Other than that I'm not down with your guys idea. Nail/screw pops are generally a fairly minor nuceance - in the big scheme of things. For the most part the fasteners could only be omitted in the middle of the sheets, and this area is normally screwed and very few (if any) pops occur here. How many nail pops do you have in your house? Many houses have them, although usually there are only a few - BFD. If there are more than that the hanger messed up and it is his responsibility - unless perhaps you use green framing lumber or something wacked like that.... Here there are code required fasteming schedules although truth be told in single family residential this is never inspected - on commercial jobs it is another story.
Siding - We use fiber cement a lot. I just had 800+ pieces installed. I just ran some numbers for my boss and for 7" exposure I think it was $165 a square with paint. He wanted to figure out if he could save money by going with pre-painted - without running any numbers I could answer that Q - the answer is NO! Really though these costs are highly regional. Sometimes I use the rule of thumb that fiber cement - by the time it gets painted is 2x the cost of vinyl and brick is >3x the cost of fiber cement. If you can get brick for close to the price of fiber cement - i'd jump on it. Nothing is lower maintenance than brick.
I can't figure out why you are shocked?
A full basement is down deep enough that the year 'round soil temp runs about 52-55°F, so not much heat differential to gaurd against. Depending on othger variances, you can gain heat from the earth. I may or may not use foam in hios situation, but I don't know the many other dtails.
IMO, the main causes of nail pops in SR are poor fastening technique, or using green or wet wood, which later shrinks.
EPS (R-control here in the states) is manufactured for ground contact with a pesticide to keep termites and ants from destroying it.
The lightest weight (Type II I think) is suitable for under slab use and it's cheaper than any of the extruded boards I've seen.
Full basement or walk out? What's you year round ground temp below the frost level? That's a consideration for how much and where to place the insulation. How much are you putting outside the basement walls?
No reason for the slab to crack if the fill is level, the foam isn't going to compress.
Joe H
Nail/screw pops in drywall are generally due to using fasteners that are too long. Lots of even "expert" DW installers don't understand this and use even longer fasteners in an attempt to prevent pops.