Advice on repairing rotten door jambs

[jameshants]

Hi all,
I have a lean-to on the back of my house and the door jambs have rotted at the bottom around 300 to 400mm in length. The construction of the
lean-to is horrible - it's an old 1970s timber frame which we intend to rebuild it in a few years so there is no point spending any more time
and money than necessary at the moment. I have some hardwood that I'm intending to put a rebate in to repair it, but I'm not sure what kind of
join would be best for this. Would you just cut at 90 degrees, then glue and screw to the frame or do scarf joints of some kind? I found
this post showing a similar join. Would a 45 degree cut be appropriate cut with a multi-tool in order to get access?

https://www.ukworkshop.co.uk/thread...ame-help-please.44035/#lg=post-580059&slide=0
Is this the best side to make the mitre?

I was going to do something similar, but glue the join with Cascamite and fix to the frame with hammer-in type fixings which seem to be
used elsewhere on the frame. As an aside, there seems to what looks like an intumescent strip around the door. Not quite sure why that
would be there on an outside door - the main house is cob with a thatched roof and nothing is standard in this house.

I'm going to do the non-hinge side first to see how it comes out and then the hinge side where the repair will reach to just above
the bottom of the 3 hinges so the bottom hinge will need to be fitted to the repair. Am interested to see if you think this
is a reasonable way to go about it and any general tips to repair this would be much appreciated.

Thanks, James.

 

[Doug71]

A scarf joint is the way to go but I would start it high at the wall side of the frame and go down towards the door side of the frame, opposite way to the photo, theory is any water that gets in will be running out, on the one in the photo the water would run down the back of the frame.

I can't really make out the intumescent strip in the photos, could it just be a draught seal?

 

[Mike Jordan]

A 45 degree cut was the norm to stop water running inwards. Two sets of plugs and screws to hold the new piece to the wall. That was in the days when money was tight, nobody would go,to that trouble today. A new jamb or,complete,frame is quicker,and easier. Softwood is not that expensive!
If you can rebate a short length, a full length should be no problem.

 

[thetyreman]

scarf joints can be tricky, especially getting a gap free joint, I think you'd be better off just making a new frame and rip out the old one, and make sure you use a durable wood as a replacement, no point going into that much effort and it only lasts a couple of years.

 

[Petey83]

I had to do the to the garage door frame. I cut the rotten bit out at a 45 degree angle and cut a new piece of treated 2x4 to size. Fixed in place with gripfill ( not found a broblem yet gripfill won't fix) and plugs & screws. Filed over the joint with 2 part exterior woodfill and the just sanded back before finishing with paint.

It's been fine so far and I did it about this time last year.

 

[Oddbod70]

As per Pety83. For a couple of years I doubt the joint would matter. But having said that a scarf is just as easy. A good soaking of wood preservative on the end grain, if you have any, and it will easily last for the time you need.

if you can get an accurate 45 mitre with a multitool you are doing better than me! A hand saw is a better bet If you have access. stick a bit of epoxy wood filler into the scarf when You assemble It if youve made a mess of the angles.

not exactly a “proper job“ i‘ll admit, but it‘ll do fine for 5 or so years easily.

 

[britinfrance]

I agree with thetyreman - The amount of work/time repairing via scarf and so on, is probably more than whipping out the old frame and put in a new softwood frame, heavily coated with preservative (don't forget the cut joints before assembly) Job done at low cost. (recycled timber is even better) Good Luck or as we say in France - Courage!

 

[LBCarpentry]

Nothing wrong with splicing and if it’s money & time you want to save then don’t bother replacing.
Make a 45 degree cut above the rot. Prep existing timber and new timber using window care dry flex system. Slap a big old blob on one of the end grains and blob them together allowing a 5-10mm gap for the dryflex to fill and cure.
SWipe a spatula round to remove the excess and viola.

Optional extra - Return the next day, two part filler over the top (it Can sink just a little) and sand to a seamless finish.

stand back and admire your resourcefulness

 

[jameshants]

Guys,
A massive thanks to all who replied. With regard to putting a good coat of preservative on the ends of the jambs, is there any particular type/brand that you would recommend?

Also, with regard to epoxy fillers do these go onto the bare onto the wood or do I need to put preservative or coating on first?
Thanks, James.

 

[Oddbod70]

Guys,
A massive thanks to all who replied. With regard to putting a good coat of preservative on the ends of the jambs, is there any particular type/brand that you would recommend?

Also, with regard to epoxy fillers do these go onto the bare onto the wood or do I need to put preservative or coating on first?
Thanks, James.

I have a can of ronseal clear preservative. Its quite pricy compared to the stuff that you paint thefence with. but it is real preservative. Its clear, thin, ans soaks right in. It goes on before any fillers.

to be honest its belt and braces. If you dont bother I doubt it will matter too much. Not worth spending 30quid on a 5l can if you are only needing a drop.

where are you in hampshire? If you are tadley way i have a bit you can have.

 

[toolsntat]

New frames seem easier but then there's a door to re-hang and lock keep and bolts and alarm and painting.....
Cheers Andy