Best way to machine off one side of a large wood beam, in situ?

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Jonm

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It's possible that I could just build another frontage, just behind the rotten one to support the dormer gable, from inside the loft and then remove the rotten beam and replace the whole thing.
That could be the way to go. I assume you have scaffolding in place. If the cladding is removed could you build an internal temporary support whilst standing on the scaffolding. Building it from the inside would be difficult, depending on your age and mobility. Presumably it is just a case of internal temporary supports to replacing the vertical timber members at the front.

Timber cladding in that location is always going to be a maintenance liability. Personally I would either replace it with something else which does not rot or if that is not acceptable for aesthetic reasons, then have a weatherproof facade made of non rotting material with the timber cladding as an easily removable/replace decoration, with ventilation as you intend.

On my recent new build, I have dormers and went for lead cladding. It suited the property, accommodates any movement and is low maintenance. Expensive to buy but cheap to install. Tile alternative would have required very expensive external corner tiles. Timber cladding was ruled out, looking to the future I need low maintenance.
 

Jacob

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That could be the way to go. I assume you have scaffolding in place. If the cladding is removed could you build an internal temporary support whilst standing on the scaffolding. Building it from the inside would be difficult, depending on your age and mobility. Presumably it is just a case of internal temporary supports to replacing the vertical timber members at the front.

Timber cladding in that location is always going to be a maintenance liability. Personally I would either replace it with something else which does not rot or if that is not acceptable for aesthetic reasons, then have a weatherproof facade made of non rotting material with the timber cladding as an easily removable/replace decoration, with ventilation as you intend.

On my recent new build, I have dormers and went for lead cladding. It suited the property, accommodates any movement and is low maintenance. Expensive to buy but cheap to install. Tile alternative would have required very expensive external corner tiles. Timber cladding was ruled out, looking to the future I need low maintenance.
Cedar shiplap.
 

Jonm

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Keeping away from why I went for lead, a durable wood for the cladding, as you suggest, is a good idea. I assume that rich1911 wants to retain the current look, in which case it is a painted timber finish.

Someone I know had a house with a lot of timber cladding. Over a period of years he removed it all, fully painted all sides and refitted it. His logic was that timber would take up moisture through a primed back face and move, causing the front paint to crack. He thought it worked.
 

Jonm

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That could be the way to go.
Re reading your original post, the existing beam is 120 wide and the rot has gone in 40mm max. I can see why you are looking at cutting out the rot and glueing in a replacement piece of wood.
 

Jonm

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Here's what I'm dealing with.
The cladding runs vertically, I would have thought that with water running down the joint, some would penetrate, particularly with the black decorative feature interrupting the downward flow.

Perhaps others on here have some experience of this.
 

rich1911

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That could be the way to go. I assume you have scaffolding in place. If the cladding is removed could you build an internal temporary support whilst standing on the scaffolding. Building it from the inside would be difficult, depending on your age and mobility. Presumably it is just a case of internal temporary supports to replacing the vertical timber members at the front.

Timber cladding in that location is always going to be a maintenance liability. Personally I would either replace it with something else which does not rot or if that is not acceptable for aesthetic reasons, then have a weatherproof facade made of non rotting material with the timber cladding as an easily removable/replace decoration, with ventilation as you intend.

On my recent new build, I have dormers and went for lead cladding. It suited the property, accommodates any movement and is low maintenance. Expensive to buy but cheap to install. Tile alternative would have required very expensive external corner tiles. Timber cladding was ruled out, looking to the future I need low maintenance.
I don't know for sure, but it's possible the the mock tudor cladding was put on when the house was re-roofed with concrete tiles. The original woodwork would probably have been ok as would the pebble dashed lath and plaster infills.

Lead would look nice. Accoya would be the ultimate choice for new cladding. As I'm removing the old lath and plaster, I won't need to worry so much about ventilation as the cladding will be fully exposed front and back.

I'm working may way along the main cross beam, machining off the rot. I think the corners are going to be the most difficult parts as the rot likes to travel in from the ends of the beams and the corners is where the beams all meet. I have't fully exposed the corners yet either.

I have plenty of time to work my way through it though and I think I have just caught it in time. Just...

It's interesting that the front didn't look too bad a year or two ago, but I guess the rot has been there a while, eating the cladding from the inside out. This year was when it finally made it through the cladding and became noticable from the outside.

On the plus side, my new Trend 25mm router bit is cutting sooo much better than the unknown brand 15mm cutter I had before. I am clearing 30mm wide channels now, an inch deep in 3-4 passes, then taking off the 5mm remaining strip with the multitool. Still a little limited in length of cut, but actually there is a limit to how far you can go without having to stop, get up and move anyway.

The indexing on my jig means I only need to have 3 fixing holes for each section of beam. I can cut the whole width off in 5 runs. Less as I get to the end of the beam as it's got a slope on the top running down from the mid point.

Today I will going into the worst part of the rot, cutting out 50mm or so. As the cuts go through the mortises for the upright sections, I can take them out and put completely new upright sections back in.

The more I work on it, the less daunting it looks!
 

rich1911

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Made some more progress today.

Alas my new router bit found a massive iron nail, which was below the surface and invisible from the outside! I should have guessed it was there as they hold the cross beam onto the joists...

Now I just have to machine around it until there's enough of a nub to extract.

20220617_165022 (Medium).jpg


Second area machined off, this was very rotten on one place so I took off 50mm of material.

20220617_153755 (Medium).jpg
 

morqthana

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I would make the metal framework wider than the beam and build a cross sled that the router can sit on and traverse the beam from top to bottom (and vice-versa). Something along the lines of my (poor) dwg. The cross sled could be made out of timber which would be both lighter and quicker I would guess.
 

Seascaper

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Hello,
The best tool for sorting out you beam is to get yourself a Makita multi tool and a good set of blades. With the reciprocating saw you will be able to accurately cut out the old wood and use the same tool to cut in new wood. I have have to do similar work on rotten wood and bought the tool for the job. You can get into tight spots and corners without damaging surrounding areas. The blades will cut metal as well as wood so you don’t have to worry about nails and screws. Once you have discovered the “multi tool” you won’t look back,
Regards
 

rich1911

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Hello,
The best tool for sorting out you beam is to get yourself a Makita multi tool and a good set of blades. With the reciprocating saw you will be able to accurately cut out the old wood and use the same tool to cut in new wood. I have have to do similar work on rotten wood and bought the tool for the job. You can get into tight spots and corners without damaging surrounding areas. The blades will cut metal as well as wood so you don’t have to worry about nails and screws. Once you have discovered the “multi tool” you won’t look back,
Regards
I've got a multi tool but I cant imagine it cutting this size of beam (about 2.5m long, 150mm high). What model Makita do you have?
 

baldkev

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The multi tool would be good for the ends. He is suggesting a recip saw for the centre... they are a bit agricultural but can thew thru wood and metal quickly. Basically a giant jigsaw blade.

No one mentioned the angle grinder chainsaw yet?!!! 🤣🤣🤣
Wasnt that superseded by a chainsaw attachment for a strimmer? Far safer 🤥🤓🤕

On a more serious note the boatbuilders use an angle grinder carving disc which removes material fast. I have no experience with that
 

Seascaper

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Hello,
These would do the job and go through the metal. One would make a criss cross series of cuts it the wood to the depth required and the use a chisel to remove the cut wood.
Regards
 
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rich1911

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The multi tool would be good for the ends. He is suggesting a recip saw for the centre... they are a bit agricultural but can thew thru wood and metal quickly. Basically a giant jigsaw blade.


Wasnt that superseded by a chainsaw attachment for a strimmer? Far safer 🤥🤓🤕

On a more serious note the boatbuilders use an angle grinder carving disc which removes material fast. I have no experience with that
Sawing the front off from the top is not that easy in my case as access to the top face is limited by the rest of the structure. If I could get at it, I could run a circular saw along the top...
 

Jonm

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Slowly getting there...
With regard to vertical/sloping timbers you were talking about replacing them. Is that still the case or could you repair them as you are doing with the horizontal members.

Clearly the original construction was the frame with infill (lath and render) which was subsequently cladded with the vertical boards and decorative timbers. Are you thinking of going back to an infill solution or cladding it?
 

rich1911

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With regard to vertical/sloping timbers you were talking about replacing them. Is that still the case or could you repair them as you are doing with the horizontal members.

Clearly the original construction was the frame with infill (lath and render) which was subsequently cladded with the vertical boards and decorative timbers. Are you thinking of going back to an infill solution or cladding it?
Hi Jonm,

The verticals are thin in comparison to the beams and the middle ones are lose, so there's no weight on them. I'll just replace them.

The end verticals, I found out today, are very thick and form the corner support to the roof. Luckily an inch of machining cleaned the first one up pretty well. The rot is very much concentrated in the outer face and there isn't too much down the sides.

I am not 100% decided on what to replace. If I go with cladding, then the beams and uprights can be assembled however seems best as it will just be a support for the cladding and won't ever be seen again.

I dont know if I'll put the mock tudour bits back on as I think these helped start the rot by channeling rain into the cladding. The backs of the mock tudour boards were all rotten.

The other option is to go back to original, with decorative bracing, decorative panels and infilled pebbledash on laths.

Both the original pebble dash and the mock tudour are unusual around here.

Here's that end vertical post, in the pictures above after I cleaned it up today. Nice to routing vertically with gravity assist for a change!

20220707_161949 (Medium).jpg


What it looked like this morning:

20220707_132104 (Medium).jpg
 

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