Insulating floor of a 3-season porch

Nelson_4

Hi,

I live in Boston and have an unheated 3-season porch. It has been transformed into a daytime playroom and I would like to use it year round. It is 14' x 7', about 100 sq. ft. and I plan to supplement with a space heater.

It is south-facing with a lot of single pane windows. I have already made interior storm windows <a href="http://www.arttec.net/Thermal-Windows/index.html">[url=http://www.arttec.net/Thermal-Windows/index.html]http://www.arttec.net/Thermal-Windows/index.html</a> that made quite a difference. But the floor is still cold.

The floor is carpet on top of plywood. It looks like there is a layer of poly under the plywood. The porch is 3 feet off the ground but is enclosed with thin wood and plaster. I can access the area beneath the porch floor from a door in the basement.  There is no insulation between the floor joists.

My question is, should I insulate under the floor or is it a waste of money? If so, what kind of insulation should I use? (Rigid board, fiberglass, etc.) Would I need to get a building permit? 

johnnyge

foam insulation

I put spray foam insulation to and extension of my living room where the access to the floor was from a crawl space. I think is better that the rigid foam board .Find a company in your area that does foam isulation and get an estimate for the job.

Jamie Hall

Foamed in place

insulation is definetly the way to go on that one.  I have used a product called Icynene, and it worked very very well.  Try Healthy Home, Inc., in Melrose.

Nelson_4

Open-cell vs. closed-cell

Thanks for the replies. I got an estimate from Healthy Home over the phone. But the more I looked into spray foam insulation, I am more convinced that my application is better suited for a closed-cell foam, as opposed to open-cell (such as Icynene). Any thoughts on this are appreciated. 

Jamie Hall

Only comment I'd have

is that Icynene, though an open cell type foam, is air and moisture impermeable -- and seals uncommonly tightly.  Which is part of what you want.

johnnyge

foam

The foam insulation will expand and cover every crack you room may have . When i did it on my house, the foam came up to few tiny holes on the top of the hardwood floor, meaning that it will really be a tight sealer for heat loss.

kcopp

you are right...

about the closed cell. The urethane (closed cell) is a much better fit. More r value to the inch, better resistance to moisture, better strength per square inch.... many Icene contractors are now going to the closed cell

jb_14

Closed Cell polyruethane foam is the way to go.

Have used RHH Foam Systems - Versi Foam - done it with my crew.  You can do it or pay someone to do it. 



It's closed cell.  Class I for flame and smoke spread - code accepted though needs to be covered in accessible spaces.



It's rated at R 7.0



they sell kits that do 600 board feet of expanded foam (600 s.f. at 1").  It comes in kits of 2 propane grill size tanks, with a hose set and nozzle/tips.



you can spray foam all of the perimeter and up against the flooring and then finish with netted cellulose or fiberglass batts - to save some money.  the closed cell foam does it's thing by completely air sealing - as well as insulating.  it is a moisture barrier which is good for a crawl - though as I think about it you may need to put the fiberglass up first - then foam seal it all up.



Good luck