Manufactured home re-sheeting over original osb


#1

Good day all, the roof on our 1993 manufactured home is pretty wavy and some spot are very springy/spongy. I know the roof leaked in a few spots and will have some water damage that will need to be replaced. We live in the Pacific northwest.

As a whole, Would I be ok re-sheeting the roof with 5/8 plywood over the original 1/2 (could be 5/8 osb?

Or would anyone recommend taking out the original osb?

I am mainly concerned about weight. I’ll be replacing the shingles with standing seam metal roofing which i believe is way lighter than shingles.


#2

Much better to rip all the old out.


#3

Rip the old off. We go over old plank decks all the time, but when going over plywood or osb you are asking for problems and nail pops.


#4

You think your decking is wimpy,
Wait untill you see the trusses.
I would tear off the roof first.
And consider just
replacing your rotten wood.
You may find that all the trusses are only
1 1/2 inches x 1 1/2 inches.
You may find that the old plywood was stapled.
The 8d ring shank nails we use now would blast those trusses apart.
You cant stand on them either.
Proceed carefully.


#5

Every manufactured home I have removed decking on has had at least 1 broken truss.

I don’t recall how many but more than 10.


#6

I would replace the rotted deck sections with like kind and quality so the profiles match. As stated by others you’re asking for trouble if you ripp it all off. If you replace all or repair sections of decking the most important thing is; cover the entire deck with a good deck barrier (Ice & Water or Base Modified). I’d recommend GAF Weather Blocker (Mineral/Fiberglass surfaced) or StormGuard (Durable film surfaced) Ice & Water barrier their both self-adhering and very easy to apply, no fasteners just peel and stick. Both sold in 2 (201 sq ft) square rolls.


#7

Most manufactured homes I’ve seen have 3/8 decking and are a 3/12 pitch. If they have a lot of water damage I have added 7/16 over the existing deck and then covered the roof in ice & water shield such as weatherlok or stormguard. The roofs are solid after that. We even had a tornado go through an area that completely destroyed some of the homes and blew off decking on others and the 4 month old roof didn’t lose a single shingle. Like the others said though it will depends on the framing if it’s buikt for the weight so verify that first.


#8

Thank you all for the replies.

I suspect the trusses are 1.5 x 1.5. I take it that replacing all or portions of the original deck is somewhat tricky trying not to damage the trusses. Sounds like a disaster waiting to happen :smile:

Do they usually glue the OSB on as well as stapling it?

If I plan on installing standing seams metal roofing, I am going to have issues with the wavyness of it all. Any thoughts?

I currently have plain shingles on. The roof line is not very steep and water seems to run uphill under the shingles. I have two leaks right now that I cannot figure out for the life of me where the water is coming in. I saw that some shingles were nailed in on the tar strip and I can see water passed the strip. Likely the water is coming through the nails is my guess. Thoughts?

Thx again!


#9

If the trusses are 1 1/2 inches square
And you are determined to remove the decking,
I would buy some 1 1/2 x 1 1/2 and have it on hand.
Also i would screw down the decking
Instead of nailing it.
That way you can secure it without blasting the trusses apart with the nails.

By the way, i dont replace decking if it is not water damaged and just has a slight dip.
I can fill in that dip and make it plane with just thoughtfully laying a few shingles laterally in the dip.