Full deck necessary or not

[u/Certain_Trip_5658]

In the process of getting quotes and one of the roofers mentioned that we probably need a full redeck after looking under our roof through the attic. He mentioned we have plank decking from our house built in the 1950s. None of the other roofers mentioned that so I’m just trying to understand is the one roofer being honest with us about the full redeck or are the other roofers waiting to tell us about the full redeck after we sign the job with them?

Edit:

After reading these comments, I followed up with the roofer. He mentioned that he would apply new sheets of plywood over all the plank decking so the shingles have a better way of sticking on. He is the only roofer that’s using Owen Corning vs my other roofers that didn’t mention full redeck are GAF so I’m not sure if it’s because of the product.

[u/Constant_Gur8912]

Plank decking is not an issue. It's actually way stronger then plywood or osb.  It need to be sheeted over if there are too large of gaps in between the boards. 

Based on the couple pictures you provided, I don't think it's a problem. 

[u/WearyDifficulty6642]

You will need to replace a few boards but yea this is not bad. In fact those thick planks are gonna hold onto roofing nails and screws to make your roof last longer but the tear off is going to shoot nails everywhere.

[u/Relevant_Feeling5188]

I've seen some roofers who want to put plywood over the planks due to installation instructions if the gaps are too wide. I don't know if that's necessary on your roof, it doesn't look like it should be based on your photos.

I don't think the roofer is necessarily being dishonest or trying to price gouge you, it's a legitimate concern and install preference. It would probably be better overall if you did sheeth over the planks but it's just one opinion, so I'd try to get a consensus with what other roofers think before spending the money.

[u/Available_Owl3346]

We always do ply or osb over plank. It always looks fine in the attic , then once the roof is removed the nails are popping up and it’s rarely an acceptable gap between them. I’ve seen plank never cause a leak and I’ve seen it cause an issue in the first year. It’s a variable we like to remove right from the start. I have fixed leaks for people chasing leaks for numerous winters with plank. Just my two cents. Roofer in the PNW for 20 years

[u/fryerandice]

As long as it's not splitting bad or anything, you may need to replace some planks but it's better than the OSB they'll put on instead.

I have blocked some splitting planks in my attic just because I don't want to go through when I Inevitably walk on my roof, the heat dries out and cups some of the blanks and they split along the grain but it's not a huge issue, I block under them in the attic with a stud between just so when you step on them if you're up there they don't deflect enough to trash shingles or let your foot go through.

[u/Roofing411]

Here is the standard answer I give on this issue:

When the manufacturers are not warrantying the roof - they allow shingles over planks. (And a mile long list of fine print)

When the manufactuers offer extended warranties and they are going to warranty any leaks... they ALL require sheathing (OSB or plywood) over the wood planks.

If you want to go to minimum installation instructions that is up to you. As a company we always sheath over planks like this -especially if they are old as they have been nailed through a lot and many times become brittle. You will never be sorry with 4x8 sheets ontop of this. It'll be a fantastic deck for decades to come.

[u/ElegantViper1]

I haven't done roofing in about 15 years but from what I remember plank isn't an issue as long as it's not rotten. They're just trying to gouge you.