I am replacing damaged (split) 1×8 v -rustic wood siding. I am planning cut out damaged sections of siding and replace with new boards, priming all bare wood and flashing behind the butt joints with bituthene.
Should I leave a slight gap at the butt joints, insert a piece of closed cell foam (bond breaker) and then caulk, OR butt board ends with no gap?
I know that boards don’t expand much along the grain, but some of the siding runs are thirty plus feet long.
The painter says to leave an eighth inch gap between boards ends.
thanks
Replies
"The painter says to leave an eighth inch gap between boards ends."
That's probably not what I'd do. All of the V-rustic I've installed (miles of it) has been redwood, which shrinks for length slightly, so you get gaps even if you don't start with them. It's hard to paint gaps so that they look good, and I wouldn't start out with gaps unless for some reason I expected the material to take on moisture after I installed it. You should definitely back-prime everything. In any event, talk to someone very knowledgeable at the siding supplier, and find out what they recommend for the material they're selling you and what other people's experiences are.
Bituthene is thick enough to cause a bulge if you just put in a small piece. Vycor is similar but thinner. I assume you want to use sticky stuff because you can't easily get felt in there properly lapped.
Thanks for the information regarding shrinkage - yes, I am using redwood (clear A).
The house may have some moisture problems... since some of the damaged siding is buckled and the paint has some problems... some of this may come from problems that have been resolved already and some may come from no flashing at the buttjoints. I will have to decide about whether or not to space.
Thanks also for the tip about Bituthene causing bulges. That is just the sort of thing I would have learned the hard way (ugh). I have read that felt can get brittle and that is why I planned to use bituthene... I will get Vycor
Again thank you
Adrian Garsia
we like to install all wood horizontal siding with a bevel joint.. usually a 45....
and end prime both ends.. then install tight, but not forced
Mike Smith Rhode Island : Design / Build / Repair / Restore
Hi Mike
Thanks for your reply.
I can see why a bevel joint would be superior, as it would allow for slight movement at the joint. Since I am replacing individual pieces of siding I was thinking that it would be challenging to make a cut into the existing siding with the blade at a bevel. I will think more about how to cut such a bevel...
thanks again
Adrian Garsia
skill saw, fence / table tilted to 45*, finish off with sharp chisel.
regards
james
*edited to add ..... plunging is kinda weird, so practice on a few peices of scrap first.
Edited 1/30/2004 11:16:29 AM ET by james
"it would be challenging to make a cut into the existing siding with the blade at a bevel. I will think more about how to cut such a bevel... "
A little 3 3/8 circular saw is great for this sort of thing. Handy tool to have for siding work in general.
I just picked up a $15 pull saw, it has no back band because it doesn't need it so you could hold a small square on the piect ot be removed, start the cut directly against the upper piece and pull the saw at the correct angle. Obviously you'll need to chisel out what's left under the piece above.
Thanks for the tip. I suppose I could set the bevel angle on the saw, loosen the depth control, pull the blade up before starting the cut and then lower the saw blade in to make the cut. I think I will try a practice cut somewhere.
Adrian
The way to do this is to guide the saw by placing another piece of siding (upside down) under the saw base to produce a 'non-compound' 45 degree cut.
Hope my description makes sense...
Your description makes sense. The siding I am cutting is v-rustic and is not beveled. My concern is having to plunge the saw in at a 45 degree bevel (since there is siding above and below that I don't want to cut). I think I will feel better once I practice the cut...
One other related question - how do I nail at the joint without
splitting the wood... I assume I need to drive nails on either side of the joint and pre-drill first. I suppose I could stay an inch back from the joint and pre-drill and screw into the sheathing instead of the stud... Anybody have any opinions on this?
thanks! Adrian
Hmmm. I see. Not sure the circular saw will work very well, then. Have never worked with that material.
As for nailing, I would pre-drill as far away from the joint as practical, and run longer nails into the stud at an angle. One nail per side would probably be better than 2 in terms of splitting. I have taken to backing up splices with a short length of self-adhering membrane, though feltpaper or metal is more practical if you have to slide it up from below.
adrian.. we always try to make our joints on a stud..
now.. if it's beveled siding then we make our 45 straight across.. which as stated above turns it into a "compound bevel".. as long as you make all cuts in the same orientation, then the compound bevels will all match up..
a nice thing about this is that it more or less replicates the way the clapboards wre cut on the colonial houses... all of their joints are compound bevels.. of course they were cut with a siding hatchet ( no word of lie)
another thing about horizontal siding... there is only ONE nail in the course..suppose you are working with 1x6 bevel siding ( clapboards).. they actually measure a little more than 1/2" at the butt.. and are 5 1/2 wide.. designed for 1 1/2 " overlap...( 4" exposure)
so the ONE nail will be driven about 1 3/4" above the butt... just clearing the top of the clap below it..this mean that every course can expand and contract without splitting...
this is contrary to what a lot of people are taught.. they hard nail the but so it will look good.. but come back a year later adn a lot of the claps will be split
with your scarf joint ( the bevel end joint).. you again need only ONE nail... not two.
only nail the overlapping joint.. this will trap the part below it.. the trapped clap is free to move.. lengthen and shorten , with the changing weather ... with a little practise you can find just how to place this one nail so it will not split the end
but hey, whadda i no ?
Mike Smith Rhode Island : Design / Build / Repair / Restore
I'm wondering if it wouldn't be better to skip the bevel cuts and the circular saw and just make butt cuts. IIRC these are patches and they're going stand out somewhat unless you go to extraordinary lengths to stagger the joints and make sure that the siding is the EXACT same profile. If you decide not to use a circular saw try screwing a block onto the siding to be cut and using it to guide a cut with a japanese saw. Look for one called an 'azebiki' that's designed for pocket cuts. My main goal would be to leave the paper intact under the cut if at all possible.
Anyway, I've done finish work for most of 20 years and would not try plunge cutting bevels into siding--guarantee it'd be ugly if I did that.
Hi David
After reading Mikes message describing the benefit of a scarf joint. I think I am leaning towards trying my hand at cutting a bevel into the existing siding - and yes, based on my own experience with a circular saw plunge cutting at a bevel is tricky if not nearly impossible. I will probably end up using the block and japanese saw technique (which I have used successfully to make awkward cuts).
I would prefer to damage the paper (not to mention the courses of siding above and below as little as possible.
Good point about the profiles needing to be the same and they will be close, not perfect. Its sounds like you are saying butt joints may hide the differences between the profiles more effectively? (at least my work is on the back of the house and not the front).
thanks for continuing to share your opinion about this
Adrian
Wow ... clapboards on colonial houses were cut with a siding hatchet? I would have loved to have seen that being done.
The siding I am dealing with is not beveled (which means my cut won't have to be a compound bevel) and is 3/4" thick 1x8.
With your explanation of where and how to nail I think I understand the why the scarf joint is better than a simple butt joint. I can just feel the little lightbulb in my head turning on.
The single nail makes sense... there are plenty of split siding peices that need to be replaced. The existing siding is double nailed.
thanks again Mike for sharing the benefit of your experience!
Adrian
The size of gap is relative to the time of year and weather conditions. But most importantly what My grandfather showed me was to put a 4" wide slip of 30# felt under every joint and start it an inch above the course it lies on, stopping a 1/4" to 1/2" short of revealing itself. This keeps any moisture from getting behind the siding.
I have never filled the gaps with caulking or anything else.
Edited 2/1/2004 12:26:09 PM ET by JAGWAH
i was taught to at least cut a 30 degree bevel on ends because when they do open up and they will you still see wood behind them i have seen jobs where they had put felt paper behind the butt joint and when they move apart you see black spots on the wall and if the wall is big enough it might not be too pretty your best bet would probably be to bevel the edge and slip vicor behind it. good luck with it
Edited 2/6/2004 8:42:36 PM ET by sharky
Thanks sharky
you have given me another reason to choose a scarf joint over a simple buttjoint.
Adrian
Change of thought here.I built my house in two stages(original house&preplaned addition)The first stage I sided(v grove rustic cedar)with bevel end cuts 3 yrs ago.Before siding stage 2 I noticed I didnt like the way the joints were opening up.When I did the next stage I did it like I do interior base sometimes,I made the joint tight then a hair long so I had to bow the piece to get it in.I cut a biscut slot in each end and glued the joint.Almost 2 years later joints and siding are doing wonderful.Just an idea that worked for me.SGB
Thanks to everyone who took the time to share the benefit of their experience to the question of butt joints in siding. I will be starting the job next week , I will let you know how it went
Adrian
This is just quick.....came across this thread by accident, and was surprised to see another Adrian....cuz this one isn't me, in case anyone was wondering. Heck, I was wondering.cabinetmaker/college woodworking instructor. Cape Breton, N.S
i know adrian ... i've met adrian.. i've drank adrian's booze..
lemme reassure you.. he's not youMike Smith Rhode Island : Design / Build / Repair / Restore
Ha! Actually, we drank a good bit of the booze you brang, ye tippler of Bowmore......now do you believe me, huh? huh?cabinetmaker/college woodworking instructor. Cape Breton, N.S
yeah.. i think you should deliver a bottle this august.. we can drink to andy's new endeavorsMike Smith Rhode Island : Design / Build / Repair / Restore
You want about 1/8" to 3/16" gap for caulking. If the new planks are new lumber and the pieces fairly long then they will probably shrink enough to caulk within a few weeks (provided you don't "spring" them into place). But this also depends on the weather there -- if it's cool and dry now but turns warm and wet before painting then the gaps could close up.
Within reason, it's better to have the gap too large rather than too narrow, so maybe you should try for 1/16" or 3/32" vs trusting a closed joint to open up before painting.
Do be sure to prime the cut ends. It greatly improves caulk adhesion.
Hi Dan:
You are the first person to indicate that a gap between boards is desireable. I am interested in your point of view, but I am not clear on a few things.
1) Are we talking about "planks" that are new (green?) new (air dried) or new (kiln dried). It is hard for me to imagine kiln dried wood that has been primed shrinking... I assume we are talking about wood that is air dried? It is hard to imagine kiln dried wood shrinking...
2) Are you talking about the lumber is fully primed? or wood that is only back primed?
3) You are talking about gapping butt joints not scarf joints?
I think everyone who has responded to my question would agree
that wood moves. People seem to feel the best approach is to use a scarf joint and nailing that will allow wood to move.
The impression I have had so far is that generally folks don't gap these joints.
It makes sense if a gap will eventually form no matter what I do. That I should allow it to be enough for caulking fit in and flex enough to ride out the movement...
Thanks for taking the time to help me out. I look forward to any response you may have.
Adrian
The wood movement you describe is of great interest to me.
39364.21 in reply to 39364.1
You want about 1/8" to 3/16" gap for caulking. If the new planks are new lumber and the pieces fairly long then they will probably shrink enough to caulk within a few weeks (provided you don't "spring" them into place). But this also depends on the weather there -- if it's cool and dry now but turns warm and wet before painting then the gaps could close up.
Within reason, it's better to have the gap too large rather than too narrow, so maybe you should try for 1/16" or 3/32" vs trusting a closed joint to open up before painting.
Do be sure to prime the cut ends. It greatly improves caulk adhesion.
Yeah, my gapping statement was made assuming butt joints. The idea is basically that caulk stretches or compresses elastically (ie, without failing) only for a percent of its width, so the wider the gap, the more stretch is accommondates. (Of course, you don't want the gap too wide, for various reasons, and 1/8 to 3/16" is about optimal.)
Whether you should gap/caulk scarf joints, I can't say. They will open a little, of course, as the (presumably wood) siding shrinks, but they prevent rain/wind from blowing straight through easily, so caulking isn't as necessary. Also, if the wood swells (rainy season), the scarfs will be able to slip slightly, accommodating swelling without buckling.
All wood, even kiln dried, will change dimensions over time due to humidity changes. It's really a question of how much change will occur in a give set of circumstances, and that is a somewhat regional thing.
I don't know what you mean re back primed vs fully primed. IMO, all wood siding should be primed (or otherwise sealed) on the back side before installation. Whether the front is primed/sealed before or after installation is a matter of which is most expedient for the circumstances. Edges that will "participate" in a butt/scarf joint should definitely be primed/sealed before installation, though.
Hi Dan
Thanks for the clarification. Well I am in the thick of it now... I really prefer bevel joints but since I am replacing pieces on siding where I don't want to damage the existing course of siding above and below I am plunge cutting and using butt joints. I have discovered that no matter how I try, all my joints are having a bit of a gap anyway.
From a weather proofing perspective it probably makes sense to leave an eighth inch gap on either side, use backer rod, and caulk. The joints will be more visible if I do this, which bothers me, but I want the joint to last.
Adrian