I have an old house. The decking of the roof is 1x8 boards (maybe they are 1x6 not 100%), however, it is not larger pieces of plywood like you would see on a modern home.

The tar paper is applied over these boards and then shingled over. The roof was last shingled about 7 years ago.

Im trying to figure out if that is wrong. Should the boards have been covered with plywood?

 

1xs for the roof decking was common place yrs ago and IMO better than plywood. As long as there are no big gaps between the boards and the 1xs are in good shape - it shouldn't be an issue. Are there any issues with the roof?

 

Plywood became popular in house framing after WWII. Before that planking was used almost everywhere we use plywood or OSB today. Roof and wall sheeting and floor decking were all 1" thick planks and quite often the boards are varying widths according to what was available.

 

No issues that my untrained eye can see. In fact, the board look almost brand new in excellent condition visually from the enterior anyhow.

However, you can see small gaps between the boards. The tar paper is visible. I even see some places where nails go thru the gap not driven into wood.

Is that an issue?

 

As marksr said, as long as there are no big gaps between the boards - it shouldn't be an issue.

You say they are small gaps. How small? Post a picture of what you're seeing so that we can see it too.

Roofs with wood shingles used to have gaps of roughly 1 1/2" which is why a lot of people overlay those types of roofs with plywood when they remove the wood shingle and switch to an asphalt/fiberglass shingle. I've also seen some people insert 1x2's between the larger 1x8's to make those gaps smaller. You don't want to end up with whole rows of nails that are only shot into tar paper.

 

No photo I can snap right now. When I say gaps between the boards theres 2" gaps where the tar paper is visible. Some are even smaller and other boards are butted firm against each other.

Its in these gaps that occasionally I see a few nails going thru.

Also at the ridge, along the very top its like I can see lots of tar paper... boards don't butt right against each other at the very top.

Again, if I have an concern at this point (since the wood looks excellent) its only those exposed nails that are in the gaps where its not bitting into wood... just thru the tar paper. But its not "whole rows" or anything... there the odd nail here and there that I see.

Is some of that to be expected?

 

Yeah, a 2" gap isn't a small gap. Even so, a skilled roofer caould make it work without overlaying sheathing... if he avoids the voids, watches where he nails so as to avoid those "whole rows" of nails in the felt paper and if he doesn't tear the felt paper in the process as he works / walks on the roof.

If the roof is already shingled it's kind of too late to question the method used. If it ever gets reshingled, I'd recommend overlaying it with 3/8" OSB or plywood.

 

Do you think some nails in those gaps should be expected? Is that a deficiency?

 

Yes, some nails in gaps should be expected. And that situation is only a deficiency if it's extensive enough, or if your mind perceives it as such.