Return to Installation
Return to Forum
I just acquired a sweet old A-Frame in southern Vermont that needs some attention and has good bones. It has an asphalt shingle roof that is mostly covered in moss, there are no apparent leaks on the A-Frame itself, but the entryway is a 10x10 kick out with a fairly flat roof 1/12 that leaks as the snow load accumulates, freezes then melts. I have not located the exact leak location, but I suspect it is at the flashing as it joins the A-frame roof/wall.
We want to convert to a metal roof and insulate from the outside. I have read that it should be treated like a vaulted ceiling/unvented roof and I have a general plan for this. 1) remove old shingles; 2) layer of decking over the existing 3/4 decking that is the interior wall; 3) leak barrier; 4) two layers of offset ridged closed-cell foam (1 to 2" each layer; 5) Decking (zip) with a barrier; 7) metal roof
My questions are many...
1) does this sound right?
2) I can only screw the decking (#2) into the rib timbers of the A-frame as I can not have screws/nails penetrating into the walls. With this added decking, will that give me a reasonable foundation to attach the rest of the system?
3) WIll this work on the entryway with such a low pitch? If not, what should I do for this area given that it is my most immediate concern?
4) Should I be thinking of some way to vent this roof via strapping at some point in the system?
5) I want to use Zip system type of product to simplify installation for me. I have one roofer telling me, "as it is an A-frame, it can be treated more like walls that roof", but when I reached out to the people at Huber, they said it is roof. Thoughts?
5) it is 20' tall and 30' long. I will have a couple of weeks in June/July to get this done. I am super handy but not a pro. Is it something a novice in roofing can/should take on?
Any help is so much appreciated!!!
Thank you for posting. Looks like a great place!
At first, I was wondering why the reason for the decking #2 but then you explained it and it made sense.
I like your plan and have a few thoughts.
I assume there is little or no ventilation at the top of this. So, moisture trying to drive out through the structure will be going through the walls. A vapor barrier beneath your added insulation is a good idea. Otherwise, we'd probably want a breathable membrane someplace similar to what would be done on walls. In your case, though, let's keep the moisture out of the insulation. The insulation then should be adequate to prevent condensation inside.
Sometimes on structures like this I will suggest a gap somehow between the metal and the roof deck to keep the metal from dropping the temperature of the roof deck and risking condensation. In your case though with the vapor barrier and the insulation, I do not think that is a concern. (Just for other readers, metal shingles which have an integrated airgap / thermal break can also be helpful in certain situations.)
As far as the roof over the porch, you might consider increasing its pitch. The only metal suitable for the current pitch is a mechanically seamed standing seam. Otherwise, you will need to use some sort of membrane roof which then is a pain to replace because it ties into the metal roof and will not last as long as the metal.
As you describe I see no need for strapping (which would be a way to achieve the airgap I alluded to previously.)
As far as the ZIP system, the Hughes folks would not like to hear me say this but I really suggest a synthetic underlayment over the ZIP panels if you use them. I just have read of problems with the laminated underlayment on the ZIP panels being breached and, with a metal roof that is going to be very long term, I think that's a risk.
Your place reminds me a bit of the following where they used a metal shingle.
Well, shoot, I don't believe that is going to load right for me -- probably too large of an image. Drop me an email at [email protected] if you'd like me to email this image to you. Let me know, too, if I missed any of your questions. I have seen people DIY such things before. The image I was trying to send you was a DIY job in fact.
If you would like to reply to this thread, please
If you do not have an Ask the Experts forum user account,