Cape Cod and 2x4 rafters

upnorthrunner · 06-18-2012, 08:13 PM

Hi all!

New here-trying to learn. My 1950 Cape Cod house needs some better insulation. It has 3' knee walls, a sloped ceiling, and a mini attic. I put as much as I could in the mini attic a few years ago and it helped. But the ceiling walls on the slope are 2x4 walls with R11 (far less in some area!) Major heat loss up here on the canadian border...

I have to yank drywall anyway. Here's what I am thinking: R13 in the bays between the rafters..1 inch foil board over the rafters on the inside, seal seams in the foil board, then sheetrock.

Would this work? Be helpful? Am I wasting my time??

Thanks for your feedback.

sixeightten · 06-18-2012, 08:43 PM

If you are pulling the sheetrock anyway, why not add framing to furr down the 2x4's farther?

joecaption · 06-18-2012, 09:08 PM

By adding 2 X 2's you could use R19.
You will need foam baffles from the top of the knee walls to where your "mini attic" starts for air flow.

upnorthrunner · 06-18-2012, 09:54 PM

Thanks, good ideas! Am I on the right track?
The biggest reason I had considered not furring 2x2s was losing the space. It's a VERY low ceiling to start...losing two inches means a lot. This place was built when fuel oil was cheap as dirt and it shows. I guess it's only another inch though.

Yes I was going to install the baffles too.

Code for my area for a cathedral/sloped ceiling is R30 which I can't get to. But i could get to about R19 with this plan. Which is a huge improvement over the current state of R 5 or so....No wonder I get ice dams! It's literally less than an inch in areas...

Windows on Wash · 06-19-2012, 09:47 AM

Blocker the joists, rigid foam and seal the knee walls, install baffles if you have soffits and intake air. If not, dense pack the slopes and over insulate the flats and the flat attic above.

AGWhitehouse · 06-25-2012, 03:10 PM

Noone seems to like this response, but it's the best option if insulation efficiency is the goal:

Put the insulation on the exterior side of the roof with "Vented Nailbase Panels". You will need to replace the roof, but you'll save all the interior space and all the crawl space funky stuff will be null & void. It solves the air sealing, thermal bridging, and roof surface venting problems in one application. Just google the name in "" and you'll find a whole slew of manufacturers.

Windows on Wash · 06-26-2012, 07:42 AM

Quote:

Originally Posted by AGWhitehouse

Noone seems to like this response, but it's the best option if insulation efficiency is the goal:

Put the insulation on the exterior side of the roof with "Vented Nailbase Panels". You will need to replace the roof, but you'll save all the interior space and all the crawl space funky stuff will be null & void. It solves the air sealing, thermal bridging, and roof surface venting problems in one application. Just google the name in "" and you'll find a whole slew of manufacturers.

I totally prefer that option, however, getting the customer to incur that expense in another question altogether.

AGWhitehouse · 06-26-2012, 08:04 PM

Quote:

Originally Posted by Windows on Wash

I totally prefer that option, however, getting the customer to incur that expense in another question altogether.

You speak the truth!

06-18-2012, 08:13 PM	#1
upnorthrunner Newbie Join Date: Jun 2012 Posts: 3	Cape Cod and 2x4 rafters Hi all! New here-trying to learn. My 1950 Cape Cod house needs some better insulation. It has 3' knee walls, a sloped ceiling, and a mini attic. I put as much as I could in the mini attic a few years ago and it helped. But the ceiling walls on the slope are 2x4 walls with R11 (far less in some area!) Major heat loss up here on the canadian border... I have to yank drywall anyway. Here's what I am thinking: R13 in the bays between the rafters..1 inch foil board over the rafters on the inside, seal seams in the foil board, then sheetrock. Would this work? Be helpful? Am I wasting my time?? Thanks for your feedback.

06-18-2012, 08:43 PM	#2
sixeightten Framing Contractor Join Date: Feb 2009 Location: NE Ohio Posts: 892	Cape Cod and 2x4 rafters If you are pulling the sheetrock anyway, why not add framing to furr down the 2x4's farther?

06-18-2012, 09:08 PM	#3
joecaption Member Join Date: Nov 2011 Location: Hartfield VA Posts: 18,822	Cape Cod and 2x4 rafters By adding 2 X 2's you could use R19. You will need foam baffles from the top of the knee walls to where your "mini attic" starts for air flow.

06-18-2012, 09:54 PM	#4
upnorthrunner Newbie Join Date: Jun 2012 Posts: 3	Cape Cod and 2x4 rafters Thanks, good ideas! Am I on the right track? The biggest reason I had considered not furring 2x2s was losing the space. It's a VERY low ceiling to start...losing two inches means a lot. This place was built when fuel oil was cheap as dirt and it shows. I guess it's only another inch though. Yes I was going to install the baffles too. Code for my area for a cathedral/sloped ceiling is R30 which I can't get to. But i could get to about R19 with this plan. Which is a huge improvement over the current state of R 5 or so....No wonder I get ice dams! It's literally less than an inch in areas...

06-19-2012, 09:47 AM	#5
Windows on Wash Exterior Construction Join Date: Aug 2011 Location: VA, MD, DC Posts: 3,855	Cape Cod and 2x4 rafters Blocker the joists, rigid foam and seal the knee walls, install baffles if you have soffits and intake air. If not, dense pack the slopes and over insulate the flats and the flat attic above. __________________ To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Cape Cod and 2x4 rafters