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Community and Q&A

Tons of questions on a remodel

punkdr | Posted in General Questions on

Hello GBA community. (Martin if this needs to be broken into multiple posts please feel free to exercise your editorial powers!)

Here is the basics on the house we are working with.

Built in 1995.  Climate Zone 5.  7400 sq feet total spread between 3 levels. Brick veneer out side.  2×6 walls with fiberglass batt insulation.  Radiant heat with original cast iron boiler.  My hope is to get the insulation/tightness to the point that the floors don’t feel warm!

I have added a 16kw solar system and replaced 8 tons of ac with 16 seer units(before I knew about this site)

I realize that the size etc is not exactly green, but, we are “recycling” this house and trying to make it as energy efficient as possible within reason.

To add to the complexity, the house recently flooded and this required gutting nearly the entire basement about one half of the main floor and not much (at least as far as the walls go) on the top floor. So, this has given us an opportunity to tackle the wall insulation in the areas that need replacement.  Anyway, I am requesting opinion on these questions regarding this renovation.

1)Basement and main floor wall insulation:  Contractor has proposed flash (closed cell) and blow fiberglass.  would it make sense to consider open cell foam fully and the create interior thermal break with EPS?  I don’t think that would cause condensation issues, but am not sure.  Also does the strategy of trying to get a thermal break going make sense on walls with a lot of windows ? Does it make sense when only half the exterior walls in a given room would be treated in this fashion and the remaining walls would be left with the original fiberglass batts?  Does it make economic sense to rip out the undamaged Sheetrock and fiberglass batt R-19 insulation to replace it with something else?

Also when taking out the damaged insulation, we found some ant nests in the basement insulation, does this change the best option?  ie is closed cell foam more ant resistant?, or should i just not worry about that and spray pesticides if I detect a problem down the road.

Also with respect to any flooding that could reoccur (we are taking steps to mitigate against that, but you never know for sure) which of these insulation choices would be the most resilient to acute water damage?

2) attic insulation upgrade:  Have the a/c ducts in the attic…also have ALOT of penetrations from can lights, built in speakers and fans.  I am planning on removing the speakers and sealing the cans from below with integrated LED fixtures.   I thought that I would use closed cell sprayfoam on the ducts and then get more fiberglass blown in (is cellulose better on top of fiberglass ?)   I don’t have a quote for this yet, but it seems that this would be more economical than making the attic a conditioned space. The attic has a complex roof line with multiple dormers, vaults etc. Opinions or alternatives welcomed.

3)  There is a large wrap around porch with a shed type roof with an attic that abuts the second story of the house and extends over the garage.  This attic doesn’t have any insulation as it is over only the wrap around porch and garage.  The ventilation is soffit only.  This set up generates ENORMOUS ice dams on the northern aspect of the roof .  Should i try and solve this problem with natural or powered ventilation? or should I sprayfoam the heck out of the underside of the roof deck on the northern exposure?  I suppose that should I choose that option it should be closed cell? or would open cell be ok as it is not over a living space?

4)  There is an old large multi panel glass sliding door that we would like to replace (12ft wide).  We have investigated a Nanawall, but these are extremely expensive.  Some of the more mainstream window makers have french door style double slider glass doors, that i think are more reasonable in terms of price…Is anyone familiar with a make that is reasonably tight, or any other suggestions balancing budget with reasonable energy performance? should we just do away with the idea of a sliding door and get a swinging french door with some adjacent fixed panels?

Thanks for the help and I appreciate the resource of GBA.

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  1. user-6774789 | | #1

    A few thoughts - IMHO your project is complex, I don't think a building science professional should offer solutions without a site visit to understand exactly what the conditions are. I always see something that was not communicated to me during conversations with homeowners or contractors - through no fault of the owner or contractor....they simply don't know.

    I would recommend you find a building science professional in your area to work on your project with you.

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