Bay window has rot in the bottom of the 6 boards which form the boxes. Going to cut away and piece in new timber lower 6-12" or so each one. Could cut 90deg and put a couple of dowels in, or scarf to increase the connecting end grain area. Or something else?
I quite like doing a scarf joint since you can then use screws into the face to bring the joint together. You can use a two part resin filler in the joint as well to form the glue and exclude any voids in the process, and fill the screw head holes (if countersunk a little).
Thanks for the advice John. Scarf- at about 45deg? The boards are about 225 wide
That is usually adequate. A more acute from the end gives more contact area, but is more difficult to cut by machine.
In some cases where there is space behind a board you can also glue/screw in a section of bridging timber to give more mechanical stability to the joint.
+1
But I prefer the space filling high strength high tack PU glues for sealing the joint since the foam is somewhat more flexible to allow for the wood dimensions varying with humidity. Two part resin filler looks neater at first but invariably cracks after a year or two.
Two part is fine over the screw heads but I have always found that it cracks sooner or later if used in a joint.
Is this joining at a piece of the original timber? If so, what's the best way to cut away the joint face?
Multi-tool, carefully hand held. Maybe temporarily screw the new timber onto the old with an overlap and make the 45 degree cut through both new and old so the cuts match up. Naturally you must allow for the extra x mm that will form the scarf joint.
On wider boards, then you can get a circular saw in there with the blade set to bevel cut. Then complete with a multimaster of fine tooth handsaw using the machine cut as an angle guide.
If space is more restrictive, then a reciprocating saw will get into most places, but you will need more manual cleanup after. (those Japanese saw rasps are fantastic for fettling things like that [1])
If doing it all freehand, then you could fix a 45 degree block to the face to use as a guide, or just freehand and eyeball. (part of the reason for using something gap filling as a glue!)
(there is a handy trick for cutting mitres by hand. You need a shiny saw, and you watch the reflection of the wood you are cutting in the saw. When the reflection shows you a nice right angle (which is quite easy to judge by eye), you know you are cutting a good 45)
[1]
In reality any glue can fail if there is differential movement between the parts. The foam of a PU glue does not have much strength though. Something like gripfil may retain some flexibility for longer. Ultimately trying to use a similar wood that will expand and contract at a similar rate, and also painting everything really well to keep the water out for as long as possible. (and ensuring things like drips, seals, and flashings are in place and working)
Thanks everyone, lots of useful information there. If I screw a guide board at about 45deg to the existing, cut through with a handsaw/multitool then use the cut-away piece as template for new that should do it? Thinking Gripfill as glue, maybe drill shallow holes in each cut end to form sort of chemical dowels. I do have a circular saw and today bought my first multitool - for the bits of sill I need to cut out and will be needed for the boards forming a box corner - but generally feel more comfortable with hand tools. Please let me know if I've made any silly mistakes with the plan! Cheers, Peter
Thanks for that (and Paul), interesting - if unlikely in my case!
Yes. Successfully
You ever done it?
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.