How To Insulate My 1 1/2 Story Roof. - Roofing/Siding - DIY Home Improvement | DIYChatroom


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Roofing/Siding

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

Reply
 
Thread Tools Display Modes
Old 08-08-2011, 04:02 PM   #1
Newbie
 
Join Date: Aug 2011
Location: MN
Posts: 3
Rewards Points: 10
Default

How to insulate my 1 1/2 story roof.


Hey all, new to the forum.

I am shingling my roof this summer/fall and have a dilemma with how to insulate my roof if at all possible.

Here is what I have, the upper story has 3' walls with a 7' sloped ceiling and a 4' flat ceiling. The sloped ceiling only has 2x4 rafters that are filled with a cellulose insulation and they are spaced at 24". As an experiment I screwed 3 inches of rigid foam insulation to the sloped ceiling on the inside of the house and it made a noticeable difference on how fast the snow melted off the roof. There would be 3 more inches of snow on the part I insulated.

I have a couple thoughts on how I could insulate the sloped part of the roof. One would be to get 2x6's and nail them to the 2x4 rafters I have now and put 4 inches of rigid foam insulation on the sloped part only. This would give me 1 1/2 inches of ventilation and currently I have no ventilation. I would then put OSB on the 2x6's and shingle the roof.

The other way would be easier, just put 4 inches of rigid ins. on the sloped part and screw OSB on top to build the roof up and shingle. This way would be easier but would have no venting.

I would really like to fix this problem because I dont want to have ice dam problems and heat being wasted. I think if I built the roof up and got it ventilated it would help to keep the heat out in the summer and keep the heat in the winter because our upstairs is cold in the winter and hot in the summer. I live in MN so winter is very cold.

Right now I figure I have 12.25 R value. If I could get some rigid foam on top of that I would be somewhere in the 36 neighborhood which would be about right.

Let me know if this is do able and if I would have any structural problems with the extra weight. Thanks

Advertisement

countryboy9799 is offline   Reply With Quote
Old 08-08-2011, 04:12 PM   #2
Member
 
AGWhitehouse's Avatar
 
Join Date: Jul 2011
Posts: 1,378
Rewards Points: 500
Default

How to insulate my 1 1/2 story roof.


If you're ripping and replacing the roof, maybe look into a ventilated roof panel. You can field build one, or use a premanufactured one. One you can check out is: http://www.hpanels.com/images/storie.../Cool-Vent.pdf

Advertisement

__________________
Life's too short...so enjoy it!
AGWhitehouse is offline   Reply With Quote
Old 08-08-2011, 04:23 PM   #3
Newbie
 
Join Date: Aug 2011
Location: MN
Posts: 3
Rewards Points: 10
Default

How to insulate my 1 1/2 story roof.


That looks like something I could make pretty easily. Will it work to run a nail or screws through 6 inches of material? I didn't know if it would work and if I could find nails that long for my roof.
countryboy9799 is offline   Reply With Quote
Old 08-08-2011, 04:30 PM   #4
Member
 
AGWhitehouse's Avatar
 
Join Date: Jul 2011
Posts: 1,378
Rewards Points: 500
Default

How to insulate my 1 1/2 story roof.


I was just on the phone with them this morning and they have screws for this type of system. I was informed that the fasteners provided for the system I linked have a pull out rating of 440lbs in 1/2" plywood and approx. 800lbs into a rafter. Have not looked into the exact specs of that fastener so I can't tell you what exact alternatives there are, but something like a timberlok is my best guess as to something close.
__________________
Life's too short...so enjoy it!
AGWhitehouse is offline   Reply With Quote
Old 08-08-2011, 04:32 PM   #5
Member
 
AGWhitehouse's Avatar
 
Join Date: Jul 2011
Posts: 1,378
Rewards Points: 500
Default

How to insulate my 1 1/2 story roof.


Just want to be sure that your roof can handle these additional loads. You stated 2x4 rafters and those can't hold much. Adding rigid insulation and an additional sheathing layer may be too much. Please look into that portion before you progress too much further.
__________________
Life's too short...so enjoy it!
AGWhitehouse is offline   Reply With Quote
Old 08-10-2011, 08:44 AM   #6
Indentured Servant
 
Join Date: Sep 2008
Location: Grand Rapids Minnesota
Posts: 129
Rewards Points: 75
Default

How to insulate my 1 1/2 story roof.


I have a similar project that I am currently working on. What I am doing is putting in ridge and soffet vents first. Then I ripped 7/16 osb into 12 inch widths. I attach to this a 2x2. In sense what I am doing is making an extension for my rafters so I can put more insulation in and allow for an vent gap. I will then put foil foam board insulation on the inside, then tongue and groove over that. Sounds like a bunch of work but it really isn't.
jackpine is offline   Reply With Quote
Old 08-10-2011, 04:16 PM   #7
Newbie
 
Join Date: Aug 2011
Location: MN
Posts: 3
Rewards Points: 10
Default

How to insulate my 1 1/2 story roof.


I just added up how much weight it would be to build up my roof with 2x6's. For the added OSB it would be 1,500 lbs and for the 2x6's it would be 1,000 lbs. I would estimate that I could remove around 600 or a little more by removing the existing boards on there now so the total would be around 1,900 lbs.

The roof is a T shape with one part 12x12' and the weight would be about 600 lbs on that part. The other roof is 12x25' and the weight would be around 1,200 lbs. Anyone know if that would be ok or how I could find out if it would be structurally sound?
countryboy9799 is offline   Reply With Quote
Old 08-10-2011, 05:07 PM   #8
Member
 
AGWhitehouse's Avatar
 
Join Date: Jul 2011
Posts: 1,378
Rewards Points: 500
Default

How to insulate my 1 1/2 story roof.


Quote:
Originally Posted by countryboy9799 View Post
Anyone know if that would be ok or how I could find out if it would be structurally sound?
A structural engineer is your best bet. There are quite a few factors involved when analyzing a roof. Wind, snow, dead load, live load, etc. Couple those with the dynamics of your existing structure and you've got yourself a bit of calculating to do to know for sure.

Advertisement

__________________
Life's too short...so enjoy it!
AGWhitehouse is offline   Reply With Quote
Reply


Thread Tools
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
Roof leak nightmare..... it won't stop amandat37 Roofing/Siding 52 04-22-2011 01:47 PM
Insulate sloped roof with dense-packed cellulose fabio Roofing/Siding 2 02-24-2011 11:21 PM
Insulate attic and between roof and closets scool Building & Construction 1 11-28-2010 03:36 AM
Replace the roof or not??? Leaked only once when it snowed chasqui Roofing/Siding 10 04-13-2010 11:02 PM
Putting a new flat roof on a 3600 sf home Jean3 Off Topic 2 04-09-2010 01:35 AM




Top of Page | View New Posts