# Re-roofing a 1984 Bowstring Truss Mobile Home



## txgunslinger (Nov 12, 2020)

First post here, but I'm a bit out of my league on this one (and relatively new to roofing, but not construction/contracting). The modern mobile home I thought the client was referring to was not (and would have been a simple job) the one he needed reroofed, but rather the 1984 POS he bought and put in his back lot. The roof is sheet metal with all kinds of cracked, old roofing sealant, plenty of old roofing cement over the truss screws. At one of the seams, I could push it down and see the truss. Where the two sheet metal panels met was all rusted.

The dimensions are 14W x 68L

Solution A: Skin the roof with 1/4" plywood secured with screws to the trusses through the original sheet metal and cover with SA mod bit roll roofing. I think the 1/4" will be thin enough to form to the rounded roof profile, but strong enough to install self-adhering mod bit over top. I am a bit concerned about weight, as I am reading these bowstring trusses are not designed to hold much. As simple as this sounds, I'm surprised by the cost just in materials - about $2300, which is already a $100 more than I quoted him originally when I thought I was just doing shingles. Granted, decking prices are crazy at almost $20/sheet (x 30 sheets). The mod bit is $100/roll for 15 rolls of cap and base. So no labor or profit yet...

Solution B: EPDM or TPO - I have no experience yet with either, but if it's the right thing to do, I'll make it happen. I've seen an EPDM install on youtube, but they redecked the mobile home first, and it wasn't a bowstring truss. I just don't see either of those solutions being applied directly over top of this rusty, dinged up sheet metal roof. There would need to be some type of sub-base installed first, right?

Solution C: R-panel - I would install the 2x4's the length of the trailer at the eave, a row or two midway and the ridge (or every 20" or something), then install the R-panel and a ridge cap. Seems like it would be not too heavy, I could extend the panels 4" past the eaves for drainage. It would provide a natural, insulating air space between the panels and the existing roof. I figure I would need 46 7.5' panels (maybe 8' long?), plus ridge cap, eave trim, 2x4's and fasteners.

Solution D: Walk away... it may happen anyway as I'm not sure he realizes the amount of work involved to provide him a roof that won't leak on this. He wanted something super cheap, and that's not me. I can't just shit on it and call it good. Cheap, good, or fast - pick two. I'm not gouging him, but I'm not doing it for free either.

Option A and C are my favorites so far, with C being my top choice. The mod bit option worries me a little for two reasons - the weight (really not too worried about that) and waterproofing and termination along the eaves.

Anyway, looking forward to any feedback or suggestions someone may have. Thanks guys, rock on.


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## roofermann (Jul 7, 2012)

Option D gets my vote.


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## txgunslinger (Nov 12, 2020)

Lol, thanks roofermann. Here's what I'm going to do... 

1. Power wash the roof (on low power to avoid getting water inside the ceiling as much as possible)
2. Install base ply right on the old, cleaned metal (probably throw a few cans of primer, and cap sheet right over that. Drip edge (4x4 or 5x5) all the way around.

Materials will cost me $1700 incl. tax, $1K for me and $250-350 for the helper for the day - $3267.00 was my quote, take it of leave it. Seems crazy for a single wide mobile home, but oh well, I'm not working for free and this particular roof design is not rated for high loads, so, this is as cheap as I can come up with and be willing to warranty for 3 years.

I sent the guy a financing link because he asked and he got approved for $2K. Now he says he needs to wait to get the balance... why not just apply for $3500 and use that? Geez, call me when you're ready I guess.


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