[Ryland]

I've been working on sealing up my house for the last two years, about 6 months ago we had an energy audit with a blower door test done and because of that we really realized how much further we had to go.
The sealing that I started out doing was just the basic feeling for cold spots and drafts, filling in gaps that I could see between my foundation and the last row of siding.
Our energy audit showed that our crawl spaces (sand stone foundation) were the worst, on a 30F degree day there were spots in our crawl space that were 37F degrees, there was some fiber glass "insulation" in there but it was acting more as an air filter, rodent nest and was increasing the area for moisture to condense (it was soggy!) so we got 3 bids and went with the one that was in the middle for price but offered 2" of spray foam, the others were 1" and 1.5", we also opted for a vapor barrier on the dirt floor with a humidistat controlled vent fan that pulls air from under the plastic via perforated drain tile (black plastic drainage pipe), this type of vent fan also works for removing radon, radon is not an issue for us but moisture build up around foundations is not good for any foundation.
So because we have rough stone walls ridged foam would not work so the spray foam was really the best option, it was supposed to be 2 part days to get our project done, one for installing the drain tile and plastic the 2nd to do the foam, after having the spray foam installed we were inspecting the work and realized that the enclosed sill boxes where the joist space runs parallel to the foundation had not been done, at all, then I took a thin sharpened wire and checked the thickness of the foam in the areas that they had done and it was only 2" thick in a few spots! as thin as 1/4" thick in others with a 6 foot stretch where they completely forgot to spray any foam... oops! had to convince the contractor to come back to look at it for him self before he even believed us that anything was less then prefect, after checking on their work even more we found that the top of the foundation inside the sill boxes was also an area that had been missed in 80% of the spaces.
Thing is, when you do a quick check it all looked ok, but start climbing around and you find huge holes and gaps.
5 trips back and 3 months later it's finished, the final touch up I choose to do my self with their can of foam instead of trying to explain where I found all the pin hole drafts.
Now I figured this was simply a single contractor that was doing shoddy work, then my boss had spray foam done at his house, his was even worse! done by a different contractor! this time there were holes that I could reach my arm through, see light through and loose a puppy in, again with foam being as thin as 1/4" thick in areas, at his house they came back a 2nd time that same day, but by that time I had to leave work and that 2nd time they were their they still left holes that you could see light out of and feel drafts, it was amazing!

If I were to do this again I would be very very clear with the contractor that they are responsible for quality control and I would still check up on them, it seems like they miss corners that you can't see well, grope around those corners for drafts and bare spots it is seldom the same person that does the bid as who does the work so talk to the person who is doing the work and make sure that they are clear as to what you expect from them and of course do not pay them until everything has been done and checked and check everything.

There are some contractors that do their own blower door test so they can fallow up and seal the areas that they miss, but those contractors are rare and expensive.