The Chinking Post

Alternate title: How to save $14,000 when chinking your cabin…

Introduction

I’m by no means an expert – I’m only building my first cabin. Many folks have built dozens of these. Take this post with a grain of salt – it is my experience with chinking my cabin.

However, you might find my specific situation helpful because:

1. My logs are “raw”, meaning they are not shaped – I cut down trees, peeled the bark, then stacked the logs. The result is beautiful and natural in my opinion. It also means no “one method of chinking” works. I have big gaps, little gaps, upside down gaps, knots, grooves, overhangs and underhangs. I’ve had to invent some things as I go, and it’s very specific to my situation. It’s probably near the extreme end of what you might experience for your build.
2. I’m using traditional mortar chink. It handles a lot differently than that synthetic stuff. And it’s much cheaper, and better at protecting logs from rot due to moisture retention. Since it’s made out of natural and cheap materials, nobody trying to sell you something will promote it, or worse – they’ll say it doesn’t work as well. But I have it on authority from many LHBA log home owners that natural chinking using the “Skip recipe” has lasted decades, with no degradation in the finished product. Saving $14,000 using traditional chink over the synthetic stuff isn’t a bad sales pitch either.
3. With no. 2 in mind, there are some “mudflap flairs” I’ve come up with, based on helpful hints from LHBA folks. For instance, some of my gaps are 6″ or more (see no. 1). Nails just don’t cut it to hold the chink in place in those areas. I’ll describe how to use stucco lath in these places.

Materials

• R-15 Rockwool in 16″ bats, available from Lowe’s. You can get the exact same stuff from Home Depot (minus the “R-15” tag). I swear it is the same stuff, though.

• Framing nail gun. I use a Husky. Also need an air compressor. Slip a short piece of rubber hose or pvc pipe (it’ll eventually shatter, but it’s what I had laying around, so….) over the end of the foot of the gun – about 2″ of hose, then hose clamp it – make sure the foot still moves up and down – this will shoot the nails into the log part way. You can also bang the nails in by hand. All 12,000 of them. Every 3″. Good luck, masochist.
• Hammer – for bending nails.
• Short pry bar – also for bending nails – sometimes easier than the hammer – just use the end and push the nails upright.
• Stucco lath: about $7 for a 3×6 sheet.

• Trowels, spoons, cake icing spatula (yes, really), mortar board.
• Cement mixer – probably this one, but the red one will do as well:

• 5 gallon buckets to carry the chink around, ladders, etc.
• Green scrubbies for clean up.
• “Masonry sand” or clean sand – just be consistent. Those little $5 bags of playground sand will cost a lot more than just buying a trailer full at a cement factory.
• Hydrated Lime or Garden lime – look in the outdoor plant area at the big box store. I guess nobody mixes their own cement anymore…
• Portland Cement. Buy one bag at a time when you’re ready to use it – you don’t want 5 bags sitting there for 6 months – they’ll get hard before you can use them. Keep it closed when not in use – humidity will make it hard.

Prepping for chinking

Insulation and a nail are barely visible, and then the chink starts.

1. Cut the insulation into strips that are sized according to your gap. If your gaps are all the same, yay for you! Cut your insulation into strips and shove it in. I custom cut all my strips. You want it tighter than you think, but not impossibly tight- that’ll make the insulation not work as well. Chink is heavy – if the insulation isn’t in there tight, the chink can push it out. Not fun when a big slop of chink falls through the gap in your logs and onto the ground or floor. Ideally, you’ll insulate the outside of the log, have a little gap in between, and then later (after running electrical) insulate the inside. The electrical will run in the gap behind the inside insulation.
2. Place nails every 3″. Use the pry bar or hammer to bend them at least vertical, or leaning in. You don’t want them leaning out.
3. For the larger gaps (6″+), go back and put the stucco lath in there, and use the nails to help brace the lath. I start with a larger strip than I need, staple the bottom in place, then cut off the excess – leaving about 1/2″ – 1″ bigger than I think, then push it into the gap. Don’t staple it at the top because when the logs shrink, it’ll crack your chink. WHEN it pulls away because the logs dry about a year after you move in, go back and use a thin mixture of chink to fill in that tiny gap at the top. Make sure you have enough insulation behind the lath to hold everything in place, otherwise you’re going to use a ton of chink. Insulation is cheaper (and more heat efficient).

Insulation in place, nails still need to be bent up.

Mixing and applying

It’s not my fault they are running low on sand….

I bought a ton (literally) of sand from a sand and gravel supplier on the river. Garden lime will work (powdered, not pulverized) – hydrated lime is the best. I also bought “portland cement”. I know they sell all types of concrete mixes – maybe they’ll work, I don’t know – I’m going with the tried and true LHBA method. Use the secret LHBA formula ratios as exact as you can – if you’re sloppy with the ratios, your chink will end up being different colors. Don’t ask me how I know. Humidity and drying time also affect it, but you won’t have much control over that. Throw it all in the cement mixer, let it mix dry for a few minutes, then add just enough water to make it wet and sticky.

Some folks add some latex paint to the chink. You can also colorize it – they sell stuff for this at the big box store. You could experiment with those.

The tricky part for me is getting the right consistency of the mix when I add water. Little (dry) balls of mix is not going to apply easy, but if it is too wet, it’ll slump too much. I like it about cookie dough consistency, rather than peanut butter. But experiment with it, and find what you like.

Don’t make more than you can use in about an hour – the chemical reaction between the mortar and the water starts a timer that ends with nice hard chinking. Nothing, not even water (well, ok, you can add too much and just ruin it altogether), will help if it gets too hard.

Start slapping it in – don’t work it to death at first, just get it in there. Use the mortar board to catch any stray chunks if they fall out. Once your mortar board is empty, smooth the bottom of the line first, then the top. If you notice it slumping away from the top, angle your trowel a bit to fold it into the gap. I aim for no gaps at the top of my chink.

A nice long line of chink

Chinking Vertically

I don’t think you can chink vertically without using lath. On an LHBA home, you have options for window and door frames – you can cut the gap for the frame to fit tight around it, or you can go a bit looser like I did so the gap for the chink matches the gaps in the logs. If you go tight, you would probably use spray foam to seal it – chinking can only go so thin and still be strong in my opinion.

I install lath on the vertical edges. You can cut the logs at an angle so they line up with the frame or just leave them as they are. I will probably cut mine later, and I should have done it before chinking, but here we are.

I just push the chink in and smooth with a spatula. The lath is stapled to the frame, since staples don’t really stick to the butt end of logs. Here’s some lath ready for chinking on the kitchen window frame:

Detail of lath around the kitchen window frame.

Finishing touches – making it ‘pop’

Don’t start a row if you can’t finish it before it dries – it’ll look weird if you let it dry and start a new chinking line the next day. You can however, make more batches of mix for the same row while it is still drying – when you start a new bucket, just smooth the two together. I haven’t seen any seam lines after both lines dry when I do this. If you do need to stop in the middle of a row for the day, try to end under a big knot in the middle of a row where the two logs almost touch – then you can hide the seam between chinking lines there when you pick back up the next day.

When you finish with the bucket, go back and do some final touches – make it smooth. Now is the time to work it to death. The more you smooth it out, the better it will look. Go for nice long smoothing strokes instead of short choppy ones that will leave a lot of lines and peck marks.

Once it is absolutely perfect, go back with a bucket of water and a green scrubby (yes I know they make a mortar sponge for $50 – green scrubbies work just as well, much cheaper). Carefully clean off the excess mortar on the log with the scrubby. Don’t touch the chink. Rinse the scrubby often. I don’t use tape – don’t need it if you use the scrubby, and stain the logs first.

Corners – I don’t know – do the best you can – make little balls of chink and throw them in the gap if you can’t reach it with the trowel – sometimes I just scoop up chink with my hand and push it in there. On the upside down corner areas, lath is your best friend. Get it in there and leave it alone – for the anally challenged: I get it- you want to smooth it out, but you must resist the temptation at least at first. I smooth it with my fingers if I have to, then come back when I do my final touches and smooth it with a spoon. Drier is better than wetter in this area. But not too thick, or it won’t stick.

I can’t get over how the chink makes the logs look like they are floating in the chink. The line just above the window was still wet in this photo. It turns white after a few days.

Final thoughts

Now that you’ve read through it all, I made a video showing the whole process.

Do a good job because breaking out a line of chinking after it dries sucks.