[jsalimao]

Hi guys,
I have a question regarding a cedar box that I built for my deck (first picture). It was built to store patio furniture cushions so it needs to stay dry.

However, after a few weeks of being outside the wood expanded so much that it destroyed several joints.

Also, the top of the box was made by joining cedar 1x6s. I used gorilla glue and pocket hole screws to join them. Then I filled any cracks with wood filler. However, the wood filler did not hold up and there are tiny cracks in the joints allowing a little water in.

So my first question is how do I fix the joints (second picture)? If I cut the expanded wood what happens when winter comes and the wood tries to contract?

Second question, what can I use to fill the cracks on the lid (third picture)? Preferably something clear that doesn't require sanding and re-staining.

Thanks guy, I look forward to hearing from you.

Joe

 

[HowardAcheson]

Lumber expands and contracts as its moisture content changes. I bet you used lumber from a big box. If so, that lumber is construction lumber and not completely dried. Your construction did not take the wood movement into consideration. You can't use a construction method that firmly attaches to cross grain wood. That type of construct prevents the free expansion and contraction of the wood which leads to warping, cracking and splitting and glue line damage. An example of improper construction is the top lid board that is attached across the end grain of the top boards. The edge board across the ends should in the third picture are another example. There are probably other cross grain situations that don't show in your photos.

As your lumber continued to dry, it contracted. As the relative humidity in your area seasonally changes, the wood will always continue to change.

Unfortunately, there is no way to fix or salvage your project. You need to redesign and rebuild in a way that allows the wood to freely expand and contract across its grain.

 

[jsalimao]

Hi Howie,
Thanks for your reply.

The wood expanded so if anything it was dry and absorbed a lot of moisture due to the high humidity here in NJ.

If you don't mind I would like to ask a few follow up questions. First you say the lid had a cross grain construction. Where is that? Are you referring to the trim piece on the front?

Secondly, the framing definitely contains cross grain construction but so does every house framed out of lumber. Is it just because this box is directly in the elements? How can you frame something avoiding cross grain construction?

Thanks for your time,
Joe

 

[HowardAcheson]

Yes, one of the areas I was referring to is the board around the top. It appears to be 3-4" wide. Looking at what I view as the front of the box, The grain in that board is at 90 degrees to the boards that make up the top.

Another indication of the movement problem are the mitered joints of that top board. The boards making up the top have expanded (become wider) and forced the joint to open. Solid wood does not expand and contract in its length but does expand and contract across its grain.

Whenever you have a board, or a series of boards edge glued with all their grain running in onrd direction, you can't attach a board like your trim piece that restricts the expansion or contraction of the boards that make up the top.

Yes, many construction joints are cross grain. But, construction uses nails that allow some movement in the joints. Also, you frequently see open joints on the inside and outside of building construction.

If you plan to get into building this type of item, I suggest you purchase Hoadley's Understanding Wood. Amazon will have it. It will explain all about wood and it's characteristics.

Finally, if I was building the item you built, I would be using a plywood manufactured with and exterior glue. Plywood does not expand and contract so you can attach a solid wood board to its edge without problems.