I sought input from the group a few weeks ago regarding spray foam
insulation - to DIY or not to DIY. I was advised to go the pro route,
and now I'm getting prices that seems like good advice. The mail
order DIY kits you can get seem to cost more per square inch than
using a pro. I've had 3 bids, and they've all been in the range of
$0.8 per sq foot (1 inch thick) and I believe Tiger Foam is more than
They are, however, still pretty expensive for my project. I'm not
going to use fiberglass, but reckon that would be around a grand for
materials and maybe a few hundred for labor (my GC reckons it would
take less than a day of labor to install insulation and VB). I've
heard many people say that spray foam is 2 or 3 times the cost of
conventional materials, but based on the three quotes I've had so far
4 or 5 times is closer to the mark.
Here's my question to the group. I am building in chutes between the
rafters for air flow, and will probably use rigid foam board (great
idea I picked up from this group) sitting on top of 1x or 2x strips
either side (ie attached to the rafters) to form the chute. I was
originally planning to have 4-5 inches of foam on top of that. But
can I use more layers of foam board and spray on top of that? I know
it's feasible in practice, but wondering if others here have
experience of that. If I put, say, 2 or 3 layers of foam board on I
could probably take a couple of grand off the spray foam cost. The R
value for the pink boards is similar to the foam, but the cost is
about a third. Sure, there's more labor, but it's easy labor,
something I could do and therefore FOC. I'd probably also need a
couple of cases of cans of minimal expanding foam to seal the edges of
Grateful for any thoughts.
PS - my resolve against fiberglass was increased further yesterday
when I pulled down drywall and removed existing insulation.
Squirrels, rats, mice, and a small amount of black mold. The rodents
won't get in again - I believe in not leaving gaping holes in the
soffits like the previous owner - but the smell and disgusting act of
clearing out dead bodies and their crap has left me mentally scarred.
Makes me heave just thinking about it.