Forums | Home Repair | Home Improvement | Painting | Interior Decorating | Remodeling | Landscaping


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Insulation

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 11-27-2013, 09:39 AM   #1
Newbie
 
Join Date: Nov 2013
Posts: 6
Share |
Default

Foam then Fiberglass


So we are remodeling our old house I would give it a age of probably 1930 it was moved from outside of town to its current location in 1950. Its mostly lath and plaster like old houses some of it was replaced with drywall. Its got the old lap siding that tends to get voids between the overlap and leak air. I decided to start on our second story since we living down stairs. I have gutted/rewired/insulated with fiberglass/used can spray foam to seal up the voids in siding/drywalled 1 room out of the 4 rooms 1 bathroom upstairs. We used fiberglass due to the low cost of it but now have a new idea and was wondering if it would work.

So my question is can I do spray foam 1in thick first sealing up the siding and preventing any draft in my lifetime then put fiberglass insulation in over the foam? I know I would have to compact the fiberglass a bit but the walls are also the old true 2x4 not the new undersized ones. We did consider just filling with foam completely but the cost vs fiberglass is a huge downfall.
Block666 is offline   Reply With Quote
Old 11-27-2013, 02:03 PM   #2
Registered User
 
Join Date: Mar 2009
Posts: 9,883
Default

Foam then Fiberglass


http://www.buildingscience.com/docum...l-construction

https://docs.google.com/viewer?a=v&q...SFjptmqEXxrdKQ

http://numsum.com/spreadsheet/show/21111

You will still get thermal bridging of the studs. Location effects vapor retarding, adding interior fb may work.....

Gary
PS. Welcome to the forums!
__________________
Clothes taking longer to dry?
Clean the dryer screen in HOT water if using fabric softener sheets.
They leave a residue that impedes air-flow, costing you money.
Clean the ducting in the last six months? 17,000 dryer fires annually!

Last edited by Gary in WA; 11-27-2013 at 02:06 PM.
Gary in WA is offline   Reply With Quote
Old 11-27-2013, 04:27 PM   #3
Newbie
 
Join Date: Nov 2013
Posts: 6
Default

Foam then Fiberglass


Well am I understanding the chart right. The way I understand it is if I compress say r11 by 1 inch into a 2.5in cavity it drops to 8.9R? The foam I am looking at says its got a rating of 7r per inch so 8.9+7=15.9? Still better then just r11 in the wall's. The main reason for the foam is to stop air movement into the walls letting heat in during summer and cold during winter. Might just break down and go foam all the way if its for 7r per inch 4in cavity R28 lol. How do you address the thermal bridging from the studs? We did consider adding 1x2 or 2x2 over the framing to give a bigger cavity

Also what about putting foam sheeting before drywall? Also the way I am taking what you say about thermal bridging is that once my cavity r value is higher then the 2x4 framing the gains drop drastically? Should I forget the idea of gaining high R value in my cavities for now since its a old wood sided house? The one room I have already done I used r13 fiberglass in and you can tell the difference in temp and outside noise. If there not going to be a lot of gains from using the foam I could just do like I did in the first room using expandable foam out of the can to fill in the voids in the old siding.

Last edited by Block666; 11-27-2013 at 05:38 PM.
Block666 is offline   Reply With Quote
Old 11-29-2013, 09:21 PM   #4
Registered User
 
Join Date: Mar 2009
Posts: 9,883
Default

Foam then Fiberglass


Location?

Gary
__________________
Clothes taking longer to dry?
Clean the dryer screen in HOT water if using fabric softener sheets.
They leave a residue that impedes air-flow, costing you money.
Clean the ducting in the last six months? 17,000 dryer fires annually!
Gary in WA is offline   Reply With Quote
Old 11-30-2013, 08:28 AM   #5
Newbie
 
Join Date: Nov 2013
Posts: 6
Default

Foam then Fiberglass


Alva oklahoma
Block666 is offline   Reply With Quote
Old 11-30-2013, 09:26 PM   #6
Registered User
 
Join Date: Mar 2009
Posts: 9,883
Default

Foam then Fiberglass


SPF foam is fine against OSB or plywood. Sorry I missed that you had none. It should not be used against wood siding, lap or car-decking as the siding requires drying from the back-side; http://www.articlesbase.com/home-and...ng-131102.html You need the air-space. Is there any WRB (house wrap/building paper)?

Gary
__________________
Clothes taking longer to dry?
Clean the dryer screen in HOT water if using fabric softener sheets.
They leave a residue that impedes air-flow, costing you money.
Clean the ducting in the last six months? 17,000 dryer fires annually!
Gary in WA is offline   Reply With Quote
Old 12-01-2013, 02:07 PM   #7
Member
 
Join Date: Nov 2012
Posts: 191
Default

Foam then Fiberglass


Same question here really. I'm ripping out R-13 fiberglass in a 6 inch space in favor of R-23 stone wool and less than 1 inch Foam It Green to seal. My back wall is so friggin' drafty I have cold wind coming in and the wall is 20 degrees colder than an interior wall 12 feet away when it's below freezing outside.

In my case I have studs, a wooden panel, and then the block/brick back wall. I'm thinking I need to conduit the electrical wiring, spray foam the wooden paneling, then drill behind the corners of the wood and fill that gap with spray foam so it doesn't flow around to the rest of the house. There is no chance of a draft from the other two walls (town house firewalls), so I'll isolate them from the cavity against the back wall and then just use blown-in insulation later there.
__________________
If you can't explain why, then you don't know what you're talking about. I'll keep asking until I find someone who does.
bluefoxicy is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Fiberglass insulation with foil backed foam sheathing thedudeabides! Insulation 2 02-01-2012 10:48 PM
Foam and Elastomeric coats over existing BUR ???? sunguy65 Roofing/Siding 2 02-25-2011 12:48 PM
Foam board and electrical boxes Master Brian Electrical 5 11-21-2010 07:03 PM
cellulose over blown in fiberglass? deerhunter Building & Construction 1 10-29-2010 10:16 PM
Diference between Fiberglass and Hard Foam shumakerscott Roofing/Siding 3 09-06-2008 12:16 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.