Filling Gaps Between Boards

I am trying to figure out a way to fill some gaps between boards.

In building my tiny house, I am trying to limit how much drywall is used, yet still have a decent looking home. To do that, and get the most out of my sawmills, I thought I would use plank walls for the first few feet for the second floor bedrooms. I milled the lumber to 1/2 inch thick, and made each board 6 inches wide. But being straight off the sawmill, there is some problems with that plan. Inevitably there are some gaps between the boards as the sawmill wavered. Add in a 100 year old tiny house on a fieldstone foundation and the only thing consistent in this house is inconsitencies!

I am trying to think of something to apply within the cracks to help fill them. Bondo works really good, but would be very expensive. I thought about drywall joint compound, but am not sure it is elastic enough.

Any ideas?

I'm guessing it's too late to ship lap joint the edges of the boards.  If you didn't mind the added thickness you could put battens over the joints.

Have the boards dried or will they continue to shrink?  I guess even if they are dry, seasonal humidity changes will cause them to swell and shrink so I'm guessing joint compound would crack and fall out.  Maybe some log home chinking material?

Durhams rock hard water putty.

Another option is big stretch caulk.  

Both are brand specific.  Stick with that brand.

Assuming you haven't put the boards up yet, put light weight builders paper (felt roofing) over your wall first, staple it to the studs or existing wall. One, it will stop any drafts on outside walls, two, it will show only as a black strip behind the boards as they dry and shrink and doesn't have to flex with the boards, so it will never come loose or fall out, three, this is a good thing to do on floors as it will do both of the above as well and prevent any squeaking floorboards as you walk on them. You can do this on staircases too and keep any squeaking from happening. This doesn't fill the cracks of course, it just camouflages them so they don't show.
On existing walls, simply paint them black or dark brown before you put on the boards. As cracks appear, only the dark will show through.

Grrrrrrrrrrrrrrrrrrrrrrrrrrrr…..this is a hum dinger of a building project.

We are renting our current house out in 3 weeks, so we must be in our tiny house soon. I am normally very good at finish carpentry and stuff, but I just do not have the time to be fussy with what I am doing. That means I am pretty quick with the nail gun, and slow to remove a board if it does not quite fit right. It is very frustrating from how I normally am with carpentry.

The wood has not had a chance to dry at all. They were living growing trees in February and now I got 10 of the 20 walls completed. It is progress, but at a price.

I am thinking a possible solution when they finally do dry is to use manila rope stuffed into the gaps and then stapled into place like the old wooden ships hulls were caulked. That is just an idea though.

You might want to consider chinking such as used on old style log cabins.

4 parts dirt
2 parts wood ash
1 part salt

Cheap, easy, & eco-friendly. Could then be touched up after the wood dries completely. I believe that if you used a fine clay as the dirt portion it could be troweled in very smoothly & paint would stick well. Don't hold me to that.

I'm still thinking that even after the wood has dried out, it will continue to expand and contract so whatever you fill it with will need to be flexible or under compression.

I had on old farmhouse.  They tacked burlap to the interior board walls then applied wallpaper to it. 1906 stuff. Thought it was pretty cool.

Well you did ask...  If it were me .... at this point I would call it another "what the hell was I thinking" and put up drywall like you could have in the beginning. Still wet wood you'll be chasing widening gaps and cracks for dunno how long and you've already spent more time on this than if you just put up drywall. And will continue to spend time as the gaps widen.

Our old place had wooden floors, with some pretty big gaps between them. The previous owners had filled the gaps with a mix of sawdust and pva wood glue, before sanding and polishing the floor. If that holds for a floor without dropping out of the cracks, then I bet it would work for a wall.

Michael Cox wrote:Our old place had wooden floors, with some pretty big gaps between them. The previous owners had filled the gaps with a mix of sawdust and pva wood glue, before sanding and polishing the floor. If that holds for a floor without dropping out of the cracks, then I bet it would work for a wall.

That is a good idea. I have plenty of fine sawdust from off the sawmill because it is a bandsaw mill and not a chainsaw or rotary sawmill.

wayne fajkus wrote:I had on old farmhouse.  They tacked burlap to the interior board walls then applied wallpaper to it. 1906 stuff. Thought it was pretty cool.

This house had 16 layers of wall paper on the walls!! It was one of the reasons why we chose to remove the wall board and not leave it up. The other reasons were because of my chain-smoking Grandparents that made the house smell foul, and so that we could wire the interior walls with light switches and outlets.

Generally I try to do the right thing in carpentry, which often means doing it the harder way, but the time frame on this building project really sucks. It is nice though to give a 100 year old building another 100 years of life though.

I wonder if you might try some Log Jam. It's flexible and slightly expansive. And even made for filling in uneven gaps between wood. That being said, I have not used it yet (seems like that project's on track for next summer) — so I don't have any personal experience with it. I don't know how big the gaps are, but I often use sawdust and wood glue to fill in gaps between fine carpentry projects by filling in the crack with glue and rubbing sawdust on it until it's smooth.

On the off chance you're still looking for ideas...perhaps you could cover the joints with battens?  This was the traditional way to cover up gaps between boards (I.e. "board and batten")

Hi Travis.
Did you already come up with a suitable solution?
How much have the boards dried installed? I'm not sure what the weather conditions are there. For instance is that a humid climate? Is it cold already there? What type of heat is in the tiny house? Unfortunately, my experience with greenish wood boards is fairly extensive. The first addition we added to our 1959 35" trailer house was built with fresh lumber cut from timer 500 feet from our home. We have dry conditions in New Mexico, but the temperature swings greatly, causing all sorts of havoc with Ponderosa pine lumber.
The board and batten idea is a good solution, but as you have probably already seen the boards you already have installed aren't done expanding and mostly contracting. I know it's difficult for a craftsman to wait for the quality results we desire, but you may be better off waiting until the installed boards cure before you add chinking or battens. I've seen battens peal away because of the shrinkage of the boards underneath. I've also seen chinking come out in short time because of the shrinkage.  
I hope this helps or you already figured out something.
Best regards,
Brian  

As I was reading this thread, I was thinking battens, and then I saw Peter mentioned it. That's what I would do. I did it in a shed I built with rough cut boards; it has a nice look. Since the battens are only going to be used to hide the irregular cracks, don't nail them to both boards...just one side. This will allow for any expansion/contraction.

I cannot do battens because the boards run horizontally and not vertically. I have used them extensively in the past, mostly for my sheep barns since its an easy siding to produce in volume, and apply.

The interior boards I installed in this Tiny House have gapped quite a bit however because we have had the heat on here for about a month. It is a long story, but the propane heater I had slated for this place had a bad igniter so I had an old pellet stove kicking around, dug it out of mothballs, and have been using that. I did not say I like it, but I am warm. I say that because we have already had measurable snow (5) times so far this winter, with the last storm meaning snowplows were out and about.


My pellet stove has also dried out my lumber a lot, but it was only 3/8 of an inch to start. Even the framing lumber I used to strengthen my 2nd floor stringers have cracked quite a bit from the drying going on.

In the end the solution was actually really easy, and I am embarrassed I did not think of it before: expandable foam. A few cans of that, and a sharp wood chisel, made quick work of filling the gaps.

Just a thought, since the shiplap ship has sailed... as has levering them together super tight before nailing...
You could go back and take a 1/2" router bit and a straightedge, and rout out at the gaps, taking a skim cut off the not-so-tightly mating edges.  Leaving a uniform gap to fill with a decorative moulding (maybe a half-round, or bullnose edged strip) that you would of course make up from some dry wood. ;-)
You could do this anytime, especially since the expanding foam would cut easily.

My mom's house has horizontal wainscotting made of 2 - 12"boards and a thin strip with a bead in between. I originally thought it was T&G with a bead at one edge, but found the truth when working on refinishing the windows.
The wainscotting is capped with a chair rail which doubles as the inside sill of the windows... there's a small scotia moulding below that, and wood base at the bottom. It looks fancier than just boards with the bead in the center.

Or use that manilla rope and make it "nautical", maybe go down to Thomaston to the prison store and get some carved nautical decorations... (if that's still there).

Incidentally, a lot of manufactured paneling calls for a 24-48 hour acclimation time in the space it is to be hung (probably to swell up) so it won't buckle after it is installed.
You've got the opposite going on, but any time you can stand to wait and let your wood dry will reduce the further shrinkage. (which of course you know.)