Dealing with clapboard - separating corners

[TexasRed]

Mick Gibson and Nicholas - I appreciate the vote for bondo. It seems like a much more stable choice than simple latex caulk. DH seems relieved about this as a solution.

Off the top of my head, I don't think I've ever seen *original* mitered wood clapboard corners. If I did, it didn't stick with me....

Olsen - Hmm, I can see your point about "original mitered corners", however these are consistent throughout the 12+ outside corners on the house. FWIW, they aren't exactly mitered, but beveled.

Thanks for sharing your thoughts on the corner boards. I'm willing to try the screws and bondo products as suggested by others first. DH would rather go with corner boards - I think he prefers tight, tidy corners too.

....Installing corner boards seems like a really big job with loads of potential headaches. Same with the metal caps, though they may be a good solution for areas that are the most compromised. This is speaking as someone with no clapboard - only my opinion speaking here ? If it ain't broke don't fix it.

Thank you Willa. I appreciate (and agree with) your thoughts. You have done some amazing work in a short amount of time on your new house. We all have to do what's reasonable in scope and expense.

Shrimpdip - thanks for the photo! DH has been trying to describe these to me after seeing them on a fancy old house in KC. Another option to consider.

[JRC]

From an architectural point of view, I would try as hard as I could to stick with the original detail of the beveled clapboards.

I see the beveled clapboards as an original detail that the architect/builder of your house felt was important enough to the design of your house to use. For me, replacing this detail with corner boards wouldn't be much different from removing brackets or dentil moldings.

[Kashka-Kat]

I think "bondo" is some sort of epoxy based filler product, correct? I think you need to do more than just fill the void - theres a two part epoxy system by Abatron which includes a liquid hardener thats absorbed into the wood and also serves as a primer or base to better adhere the filler to the old wood The end grain is more absorbent than the side grain so the ends of lumber are more prone to warping,d rying, cracking, etc. ..... and then as it grays and rots it becomes even MORE absorbent like a sponge, which wont hold paint or the repairs

Theres some labor involved - drilling holes into the wood to better saturate it with the liquid & then filling and shaping the wood filler - but its something a homeowner can do easily enough. I dont know about you but I like to do what I can, and then have more $$$ to pay someone else to do things when I need to! Theres other products besides Abatron - but i would not use the Minwax version - it really sucks!

[Mick_VT]

IMO you should only need that liquid epoxy stuff if the claps have started to rot. From the looks of the picture, they are just old and dry. I have a strong suspicion that if you are careful, clean out behind them a bit from underneath and then pull them back together, almost no filling will be needed

[phil]

I think "bondo" is some sort of epoxy based filler product, correct?

no bondo is a polyester based product, not epoxy.
yes you can drill holes or if you have knot holes and things you can set a screw head below the surface and inside the repair area to give it something to bite onto.

I think epoxy is more suited to rot repairs, it is usually more liquid and able to soak in but there are obviously various brands of both, If I had to fill a hole and sand it level , it would b much easier to sand the bondo and bondo can be easily shaped with a bondo rasp when it is still in it's plastic state before it really goes hard.

If you made a boat, You'd use polyester resin and fiberglass for that. epoxy is too expensive and it is more flexible and you would want your boat to be more rigid. But if you put a hole in the hull and wanted to do a repair the epoxy and fiberglass would be favored as it has stronger bonding strength and so the repair will be more reliable. epoxy is about 3x as expensive as polyester resin.

I agree it is often best not to use it especially if it isn't' really needed but in some cases it's appropriate. I have a railing on my porch that has a sawcut where someone tried to use it like a sawhorse and cut it half way through for example. I could use either but I'd clean the sawcut first, maybe with another slightly deeper one.

these products wont' stick to plastics or paint so it's best to rough up the wood. you could use something aggressive like a belt sander with coarse grit or maybe an angle grinder to get a rough surface. bondo is made to stick to metal and if you rough it up or etch the metal that helps. If water can get into the repair it is possible to see separation if water can get between via capillary action it will then freeze and push things apart. Wood wont' absorb and stretch and shrink as it first did if it is saturated with it and you can get failures if the wood stretches and shrinks and the resin isn't' able to since it isn't' a porous surface. If you completely saturate all sides it may keep the water out. On something like a fiberglass deck the fiberglass keeps the wood completely dry but other repairs might not offer that sort of protection, like the corners you speak of. If you had a little corner missing or a big knot hole I'd use it, or bondo for that. for repairs that are structural , epoxy may be the better choice depending what it is.. If you broke the handle on your shovel and wanted to glue it back together I'd use the epoxy as it is stronger.
bondo is a trade name and there are different varieties for different purposes as well as different brands. some varieties are easier to sand and there are various weights. I think bondo is made using talc as the filler, but some other products are made with glass beads or other fillers.

I'd suggest talking to a fiberglass shop rather than buying specialty products. I got hold of some buckets of epoxy. it is a liquid I mix 1:3 and takes overnight to dry. sometimes I mix it with wood dust to make a filler. the 5 minute epoxy sets faster. it wont' cure in 5 minutes but that's the expected working time once you mix the two.

The epoxy I got was actually for finishing cement floors but seems to work well for most things. you can get the little syringe things or slightly larger bottles from the big box places but you really pay a lot more this way. If you need much, Id try the fiberglass shop as they will have more knowledge of the different products and more competitive pricing on larger quantities. you may find a host of different products that use epoxy as the bonding agent but some of these products may be little or a lot more pricey as you pay for the branding/ packaging etc.
these products , epoxy and polyester resin have no strength on their own. the strength is only in the bonding strength. a fiberglass boat gains it's strength from the fiberglass. the polyester or epoxy is just the glue that holds it together. the less saturation the more strength, as long as there is enough to bond the fibers.

I don't think epoxy and fiberglass have UV protection. usually boats and things are coated with gelcoat. Gelcoat is a polyester paint and it will bond to fiberglass in such a way it cant' peel like paint can. it also provided the UV protection which is necessary for it to last. It is the gelcoat that makes a boat waterproof. If you were to coat outdoor wood you'd also want UV protection. You can paint it , it just won't stay on quite as well as gelcoat.

[Kashka-Kat]

If epoxy is more flexible imho that might make it a better choice for house repairs - what with seasonal movement of the wood.

I guess the question would be how does one define rot - imho if its soft & punky & gray & doesnt hold paint & if the liquidt soaks in easily then I would consider it rotted enough to benefit, but if you put it (wood hardener liquid) on it sits top and doesnt soake in, and if the wood is not gray and it feels qualitatively harder/denser then its good.

On one website when I was researching (sorry forget which) the guy said he preemptively treated all his exterior wood with a thinned down version of liquid epoxy (more like a liquid, and not thickness of paint) and he soaked the ends of all porch posts as well. I guess I would say that may be overkill but on the other hand, I dont think theres any harm done by using it liberally (aside from the expense).

[Nicholas]

Re thinking this, I agree, Bondo may not be as suitable for marrying up in that situation with severe weather expansion contraction, something more flexible may be needed.

[GibsonGM]

Re thinking this, I agree, Bondo may not be as suitable for marrying up in that situation with severe weather expansion contraction, something more flexible may be needed.

Just got back in here. Yes, this is why not auto Bondo ^^^^

Wood expands and contracts at a different rate than poly products, so it will eventually work loose and allow water in behind it, like a loose tooth filling.

The stuff MADE for wood reacts like wood and has a far greater chance of making a lasting repair.

Only use it if you need it. There's nothing wrong with caulking if you do it right and use quality materials.

If you have soft areas, a wood hardener may be more appropriate (Abatron products).

I prefer to get the claps or affected trim back on, then deal with any gaps as needed. The whole idea would be keeping water and insects out. How far you go depends on a few factors, such as if it is facing the weather and so on. If it's really punked, replace the board.

[phil]

I think bondo and epoxy are ok for some spot repairs. You chipped a corner off an otherwise good board and dont' want to replace it. or the bottom of a window has some rot and it is easier than making a replacement window, things like that.
flexibility and rate of expansion are two different things. wood is porous and takes on and gives off water and shrinks and stretches across the grain, a coating wont' stop wood movement unless it also stops the transfer of moisture. soaking whole boards might improve longevity if you coat all 6 sides but if not, then it may lead to more warping. cost would be phenominal to soak all your siding in it. I did my outdoor deck and front porch but that was fiberglass and polyester resin, It's different because there is no way for water to easily get between and I think both porches will last a long time as a result but to do that I had to start with new plywood otherwise delamination would be a risk. screw indents have to be filled with bondo. it has to be clean. a cant strip along the house prevents runoff in that direction and I used fiberglass drip edges on the other three sides. to prevent a bump I routered off a bit near the edges to make the drip edge sit flat to the wood. I increased slope to prevent puddling. It's a better alternative to a vinyl deck and while a wood deck would be more authentic to the house it wouldnt' provide dry space underneath and needs to be repainted every 2 years or so in this climate.
If you compare to fiberglassing on wooden boat forums they have lots of info and deal with a lot of similar situations to old houses such as boards that are difficult to replace due to size and shape, position of attachment, etc. You can fiberglass the hull of a boat but that can result in a boat inside a boat and if water gets between it pretty much spoils the boat, but it can be used very successfully in repairs if done with some forethought to problems like this. Epoxy is a great waterproof glue so it is good for repairing splits and things. its great for laminating wood. If you wanted a curved beam you could cut thin strips and re-glue it into an archway for example. you might use it to preserve some punky wod if you get it deep into the pores and a vacuum bag would help that but if all you are doing is painting it on the surface you are just sticking it to the outside of the punky wood and it wont' have the strength to hold the bond since the wood itself will fail just beyond where it penetrated.
often fiberglass boats fail and can be had for free. sometimes they get parked out in the rain and fill up until the wood bulkheads get soaked and rot. sometimes the transom which is like two layers of plywood gets penetrated by water and they rot until the transom can't take the stresses of the motor. My brother had one like that and replaced the plywood and epoxied it in place along with fiberglass.. It saved the boat. these structural wood pieces are fine as long as they are sealed up, until there is a little crack or something , it doesnt' take much. when the wood gets soaked they rot.

[Gothichome]

Nicholas, my take on this repair. I noticed the gap gets bigger as you go down. I would see if some thing more is going on here? I would see if the corner separation is actually starting a couple studs back from the corner. Are the boards starting to pull from there. If so I think I would start drawing the boards in a couple studs away working to the corner. Use modern screws in galvanized or one of the other rust proof finishes. Sink then just below surface and fill. Also, I don't think I would draw them in in one shot. Screw, give it a day or two and work your way to the corner. Use a good quality calking , prime and paint. A good dose of blot (linseed oil and turpentine) on the end grain of course.