# Sealing plywood joins/gaps in a plywood sided shed



## gak1952 (Sep 10, 2015)

How do I seal/fill the space/gap created where the plywood sheets I have used to side my shed meet?

I have built a 16’x8’x8’ shed sided with ½” plywood siding. Initially, I intended siding it with cedar planks. Consequently, I did not put any weather strips between the plywood sheets where they joined. 

Unfortunately, I have changed my mind and now plan leaving the ½” plywood as the siding and will stain it.

The plywood sheets are attached horizontally.

The two 16'x8' sides have four 4' x 8' plywood sheets running horizontally i.e one 4'x8' sheet is on top of another 4' x 8' sheet. Next to these two sheets are two other sheets with one 4'x8' sheet being on top of another 4' x 8' sheet.

On the back there are two 4' x 8' sheets, one sheet being on top of another i.e. they are attached horizontally.

On the front side I did the same as the back and then cut out a 4' x 6' doorway.

There are 2" x 4" vertical studs every 16" all around the shed on the inside. I put 2" x 4" horizontal pieces between the vertical studs where the horizontal plywood siding joined.

How I can I fill in/seal/cover the join between the plywood sheets that will now be the siding? 

I am thinking of gluing and nailing some ¼”x ¾” baton over the joins, but I would also like to put some filler in the joins themselves. Should I put some caulking/wood filler/MH Ready Patch or similar products in the joins before I attach the batons. 

I thank you all kindly for any suggestions you might have.


----------



## Masterjer (Nov 6, 2012)

You can use a bead of silicone in the gaps. I also like your idea of battons to cover the gaps. That can be a very nice look.


----------



## gak1952 (Sep 10, 2015)

*More details!*

Here are some details I should have included in my initial post.

The plywood sheets are attached horizontally.

The two 16'x8' sides have four 4' x 8' plywood sheets running horizontally i.e one 4'x8' sheet is on top of another 4' x 8' sheet. Next to these two sheets are two other sheets with one 4'x8' sheet being on top of another 4' x 8' sheet.

On the back there are two 4' x 8' sheets, one sheet being on top of another i.e. they are attached horizontally.

On the front side I did the same as the back and then cut out a 4' x 6' doorway.

There are 2" x 4" vertical studs every 16" all around the shed on the inside. 

I also now remember that for some reason - possibly to allow for better attaching pegboard - I put 2" x 4" horizontal pieces between the vertical studs where the horizontal plywood siding joined.

Accordingly, there is backing for either caulking, wood filler or some other kind of wood substitute to fill/seal the gap between the plywood joins! 

I'll also try and load some photographs once I get my camera back from a friend I lent it to.


----------



## FrankC (Aug 24, 2012)

I would go with the batons, if you like that effect, caulk first then fasten batons, you will have a weatherproof covering.


----------



## GrumpyDave (Dec 16, 2015)

If you run baton boards horizontal, you will create a trap for water to get behind. Even if you caulk the joint, eventually the caulk will fail. If possible, pull some of your nails at the lower edge of the upper plywood pieces and slide a drip cap flashing behind and re nail


----------



## Steve Neul (Sep 2, 2011)

Since you have the sheets running horizontal I wouldn't apply strips over the joints. With wood movement you could never keep the strips sealed and it would hold water and rot the plywood and the strips. I think you would be better off with a rubberized caulk in the joint. Had you installed the plywood vertical you could have put strips every foot or so it would look like siding.


----------



## GeorgeC (Jul 30, 2008)

Masterjer said:


> You can use a bead of silicone in the gaps. I also like your idea of battons to cover the gaps. That can be a very nice look.


Exactly the way I would do it.

I would overfill with t he silicone and put on the battons while the silicone is still fresh.

Georoge


----------



## NickB (Sep 24, 2013)

The horizontal seams needed a z-channel installed before fastening. That's the only way to keep the water out permanently. 

If you decide to run a horizontal batton, caulk the seam first & sweep it smooth. Then fasten the batton and caulk only the top. That way when the caulk fails, it will at least allow the water to (hopefully) run past the seam and out the bottom.


----------



## woodnthings (Jan 24, 2009)

*I wouldn't like the battens*

A 8 ft X 8 ft square with a line running half way down and through is not my idea of "looking good". I would just caulk the seam pressing the caulk into the gap, wiping it out leaving a ting radius and then count on recaulking every 3 to 5 years... no big deal. As long as the edge of the plywood is sealed from the caulk you won't have an issue... hopefully it is exterior or PT plywood. You will also need to repaint or use a solid color stain for the longest lasting condition.


----------

