Guest User
2/18/2017
I have been reading your Q/A forum and would really appreciate your advice on a project I am about to start. I have a 26 yr old composition roof and want to use battens and insulation with a new metal roof. I have noticed in some of the specialist comments they are saying that solid insulation is best with purlins. Some talking about 2x4 or 1x4. Which is best and does it have to do with insulation thickness and air gap to prevent condensation? Do you think I should use ice and snow or just 30# felt over the comp? I am also concerned about the venting . Ranch house style with half accessible attic and the other half high ceilings. They are tied together in the middle which you can see about a little over a foot between the visible open ceiling and the roof sheeting with fiberglass insulation between but the high ceiling section seems to loose and gain heat a lot. Is there anything that I can accomplish in this roof replacement that could save some energy besides the insulation between the purlins?
Eric Novotny
An informed customer is the Best Customer!
2/19/2017
Any chance you post up some pictures?
Guest User
2/19/2017
let me try to send you some
Guest User
2/19/2017
pic of open ceiling
Guest User
2/19/2017
The previous pic was the roof sheeting as it comes into the open attic area this is the open area with the truss vents and end gable vents
Guest User
2/19/2017
the roof right to left is open and the front to back has open attic with gable ends
Guest User
2/20/2017
did the pics give you an idea of what im up against?
Eric Novotny
An informed customer is the Best Customer!
2/21/2017
What part of the the roof does that T&G interior section correspond too?
Guest User
2/21/2017
the last pic of the exterior of the house you see the front double doors that goes into that large living room are all open ceiling...
Eric Novotny
An informed customer is the Best Customer!
2/21/2017
So that is the T&G section? That picture you have of the attic show a vaulted roof structure section over some insulation. If that is the area in question, there is no need to incorporate any foam to the equation. More loose fill and air sealing in that case.
Guest User
2/21/2017
The vaulted ceiling is insulated....The pic I'm sending you ....the plywood you see is the sheeting above the T&G . plywood insulation and then T&G It gains and looses a lot of heat in the vaulted area and doesn't seem to have good ventilation. I installed two solar powered exhaust fans on both open ceiling areas trying to get some of the heat out of that open ceiling area. There doesn't seem to much room to do any additional insulating as the only access is where your seeing in the pic....no gable vents on the ends.. The only reason I think I'm interested in metal is additional insulation in that area...and fires as I live in a fire area. .I can roll out insulation in the two open areas above ceiling where the blow in exists with out to much effort. I thank you for working with me on this as I am just about to do something with the roof as it is 26 yrs old with a 20 yr comp. I just want to do it once and be done
Eric Novotny
An informed customer is the Best Customer!
2/22/2017
Are there soffits at the eaves? I am sure the space is gonna be tight near that end. In order for the fans of the gable end vents to work well, you need to have the intake ventilation for supply side air flow. If you can confirm that it sufficient, I would add some additional gable vents and blow in additional loos fill insulation (Cellulose is better than Fiberglass) to cover that framing and batt insulation up for some additional R-Value. Metal will, as a standard, let go of the heat much faster than will asphalt. Just putting on a metal roof, even in the same color, that attic will be cooler as soon as the sun goes down whereas the asphalt holds that head for much, much longer. If you want to go another step (assuming the ventilation is fixed) you could incorporate some radiant barrier to go over the insulation for some additional heat rejection.
Guest User
2/22/2017
Yes there are soffits or over hang on the roof also there are screened vents on some of the ends between the rafters before the soffit. What do you think of cutting the ridge on the open areas and installing vented ridge cap and removing the solar vents? I noticed that just after the sun goes down when i need to remove the heat out of that area (the most) they don't work. I guess the smoke test needs to happen to tell for sure it is venting correctly? I use to have an auto gable vent fan that I removed because it was exactly over my bed and ran half the night in order to remove the heat out of the open areas in the over 100 degree days. The only batt insulation is over the vaulted ceiling the open areas are blow in. That is the problem, there isn't any access over that vaulted ceiling to add any additional insulation with out removing the sheeting above and still wouldn't think there was room between the sheet and T&G? Your second sentence where in you mention intake ventilation. I think I could use more ventilation. I believe the gable end vents are large enough but the side screens where the air is suppose to draw through could be an issue. Do you think I should add one between every two rafters? BTW when I get ready to blow in more insulation as suggested how do you keep them from filling up? They are nearly impossible to access at the end of that 4 and 12 roof. Could you elaborate on this radiant barrier and do you think i should remove old comp
Eric Novotny
An informed customer is the Best Customer!
2/23/2017
Most roofs are under vented when it comes to intake side of things. You need continuous and unfettered intake ventilation to allow for the convective movement of air. A ridge vent is helpful, but if it has a gable vent on both ends, it is probably sufficient on the exhaust side of the equation. A low pitch roof like that is tough to get that baffle all the way out the edge. I definitely would remove the composition shingle to help mitigate thermal mass.
Guest User
2/23/2017
Where do you buy those smoke test things and when you mentioned radiant barrier you speak of a silver reflective barrier under the metal roof? Anything recommended for that barrier.....So to sum up our talks ..You recommend ensure ventilation is good add blow in insulation remove old comp roof install underlayment with radiant barrier install purlins 1x4 and install metal roof over that correct? How about foam under roof sheeting?
Eric Novotny
An informed customer is the Best Customer!
2/23/2017
Look for a "Wizard Pen". They are the easiest smoke pencil out there. Radiant barriers require and air space to work properly. An over deck vent works quite well.
Guest User
2/23/2017
I just googled radiant barrier and it seems to be a breathable foil over the blown in insulation? That might help in my case as i do think alot of heat comes through the ceilings
Dick Bus
2/23/2017
I agree with Eric about removing the comp shingle. it also gives you an opportunity to inspect the plywood deck. Another way to reduce heat gain is with above sheathing ventilation. Oakridge National Labs has done a lot of work on this subject. install 1 x 3 along each rafter; then cross-furr with 1 x 3 spaced to the recommended fastener spacing of the panel manufacturer. keep the eave trim away from the fascia 3/4" and install a continuous ridge vent. This way you are venting directly under the panel as opposed to venting just the attic space. I hope you are using product from one of the manufacturing members of the Metal Roofing Alliance. we have all agreed to a minimum product standard.
Guest User
2/23/2017
you lost me there on the cross firring your putting 1x3 on trussses and then putting more 1x3 on top of them? or are we putting them on between them

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