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Insulating 1940 Cape Cod In MD

muggs56's picture

THE house;

~1800 sq.ft.
Cape Cod built in 1939-40.
Mostly brick exterior.
Attic well insulated not overpacked.
Storm doors/windows.
Exterior walls mostly exterior brick, facing cinder block with,
~ 1" gap between block wall and interior composite wall of
proto-drywall and plaster - NO INSULATION.

Two questions:

1. With storm windows and the window frames well insulated; what benefit from installing new windows?

2. Besides cutting holes at the top of every stud bay and blowing in non-absorbent insulation, wrapping the interior or exterior, is there
something I'm missing?

(post #113939, reply #1 of 3)

my Cape home is built very much like yours.

I replaced all the original 1948 windows with new insulated Andersens, made a BIG difference. careful measurement is the rule in a masonry house. they say air infiltration is a bigger heat loss than poor insulation.

I searched and researched a suitable insulation answer. loose fill will hang up in the narrow 1" space and not pack well. not enough room for blown in either. I settled on a slow-rise 2 part foam system to insulate the cavity. mine is by FOMO. I just got the product this fall, but it turned too cold to use... you need at least 70° abient temp of the cavity for best results. I plan on getting to it when the weather warms. SLOW RISE has to be used or it will pop the walls.

R value is 7-8 per inch. unit cost is higher than cellulose & fiberglas.



(post #113939, reply #2 of 3)

Hey muggs,

I'm down here across the River in falls church and I probably have the exact same construction cape 1948 and lots of air infiltration. Let me share some of my plan and progress with you. and please shoot some feedback here on what you think.

Alright, where to start Lets go up if you have the same 1/2 story upstairs. My main focus is air movemnet and secondary actual insulation:

1. top floor have some sort of old card board insulative? panels @ kneewalls and ceiling/ rafters in wall and ceiling cavity filled w/ old insulation of some kind. SAFETY,SAFETY,SAFETY before I move forward here I plan to send sample to lab for asbestos testing wont stop me but setup for work will vary exponentially if its positive. plan to use 1/2" styrofoam foil faced both sides over existing and tape off all joints w/ tyvek tape create envelope(also running new electric up there and surface bulid up will help w/ low profile recepts etc.) overlay all w/ 1/2" drywall. = 1 1/2" depth for my purposes.

2. topfloor built over joists w/ blown insulation (had it tested for asbestos turned out to be rockwool aka mineral wool).blown insulation has settled to 2" below bottom of top floor deck. my insulation follows ceiling and kneewalls leaving triangular cavity for air movement? hope your still with me here. So there is air movement below the entire floor second level not good!!! got a remedy from DeptOfEnergy website. Stuff cavity below 2nd level kneewall and first floor ceiling joists with plastic garbage bag stuffed with rolled up wall insulation. Remember I want to stop air if I only used rolled and suffed insulation air will sill flow through if at a reduced rate thats the reason for trash bag kind of like suffing in a balloon and insulation expands sealing cavity tight. Have completed apprx 25% of this huge difference feeling the floor with you feet finished not finished.

3. before I leave the top floor I have an old chimney That is now being used for gas appliances (quick side track will be relining chimney basically supporting dbl walled b-vent due to gas emission damaging masonry and occasionally oozing black stufff through the masonry joints but want this done before total air movement stopped carbon monoxide poisoning dont sound good) Horrendous air leaks around that thing seal it but use caution for above mentioned reason.

NOTE: I am in major renovation of this property and trying to live here as well pretty tough but most of what I am doing are areas that will be finished w/ drywall overlay etc. lots of recessed can and lots of access to this stuff.

4. Exterior walls (this is where I have apprehension but doin it anyway/ not sure if this space is needed to dry out masonry or not?????) Ext brick, then cinder block, 1x straps 16" o.c. hollow void
STraight up to attic triangular crwl space whatever its air infiltration, 1/2" drywall (what you said) and the 1/2-1" plaster overlay. Game plan use concrete hammer drill small bit drill evry 6" or so along the top of the wall and shoot expanding foam to block air flow directly to attic space (standard drill bits die fast in plaster use concrete bits). then cover damage with crown moulding.I dont really care about insulating entire wall only top and bottom.CAREFUL: shooting trim nails into plaster if its not a direct shot it likes to ricochet back through the wood watch those fingers too close to nail shot(basically shooting through concrete if its angled it will come back at you). I plan to get to the bottom of wall through basement but you could above formula for bottom.

5. windows were replaced before I got here but quality is very very bad bad. No insulation around window I did expect that and could live with it but there is air infiltration through the window assembly itself evidenced by cob webs and airflow Will have to replasce eventually like I am not doing enough things twice around here.Traco is the brand will contact them to see if proper installation was done but won't waste much time on it.

6. Caulk every thing everywhere pull capet back caulk under base leave room for carpet to go back but seal seal seal everywhere you can find. Foam gaskets at recepts and switches behind the plates.

7. Its an old house you cant get it all but hit as muc h as you can and it will pay you back inhtg bills.

Go Away, Boy
Ya, Bother Me - FogHorn LegHorn

(post #113939, reply #3 of 3)

muggs... conventional DH window with a storm window is pretty good..

 worst part is the weight pockets on the sides..

if you are going to keep the home for  LONG LONG time.. then i'd think about replacing the windows.. either with REPLACEMENT windows  ( say $500 a window installed )  or new primary windows  ( say $1500  each installed )... as you can see... if the existing windows are in good shape.. it's a tough decision as to wether to replace them or not

for the insulation.. i'd  do a top and bottom blow with cellulose...  from the inside

cellulose will give good flow in a stud bay

Mike Smith Rhode Island : Design / Build / Repair / Restore

Mike Smith Rhode Island : Design / Build / Repair / Restore