Structural mock Tudor cladding

[CTid]

Hi there
We have just found out that the cladding on the front of our Edwardian semi is structural. In many areas the wood is badly rotten and the existing render is failed. We have no idea where even to start.
So far we are thinking of the following
- survey done on the wood to ascertain extent of rot and damage
- repair and replace where needed. No idea how to do this when the wood is part of the stricture
- remove old render and re render - with what?
- strip paint off and repaint

Any advise much appreciated!

 

[Cubist]

I don't want to give you any false hopes but I am seeing clues that suggest that some, perhaps many, elements of that timber frame are Not structural components of the house proper. Among the indicators are: -

1. The most obvious is the vertical timber that has already been removed as shown in the first photo.
2. In that first photo and the third it can be seen that two heavy screws have been a has been used to close the joint between the two horizontal members.
3. However, that corner post seems to have had some major surgery in the past to insert a new section of timber in the first circa 60cm. This kind of repair is often made to heavy timbers but in itself is not conclusive.
4. Immediately below that repair I can see what appears to be a cross headed heavy screw - confirmed in the third photo?. It would be unusual but that screw could have been used to fix a tenon blade from the new section of post inserted above but conceivably this may also suggest it was used to fix the cill timber to the tail of the post.
5. In the second photo the cill beam itself seems to be just circa 100mm thick. This would be unusual for a cill plate timber insofar that it implies it cannot be directly supporting the full load of the masonry infill walls above it. Do any of the timbers comprising the frame appear indoors?
6. The fourth photo seems to be of an odd feature of the framing insofar that the joint seems to include a mitered section connecting two horizontal timbers which in turn support a vertical post while the horizontals sit on what appears to be an outrigger from another horizontal timber that originates indoors. All of which appear to be fixed together with heavy screws.
7. The fifth photo confirms that a metered joint has been used at the junction of two horizontal timbers but again this joint is fixed with heavy screws. The placement of the screws also suggests, presuming they were driven in at an angle, that the timbers are not particularly thick - I'm guessing no more than 100mm.
8. In the sixth photo the corner post to the left has clearly been constructed in two parts using a lapped joint. Of itself this is not unusual but the pegs apparently used to wedge and lock the joint appear to be in the wrong positions.

Sadly the frame has been constructed of a softwood, pine almost certainly, and barring for the corner posts of the structure, I suspect that all the other timbers, with the exception perhaps of the cills, are no more than 100mm thick and some of them maybes as little 50mm. The builders, in using heavy steel screws, to fix many of the joints have contributed to the decay because steel and the woods tannins do not do well together - there is a good chance that many of the screws have corroded almost to nothing. Very clearly a cement based render has been used to coat the masonry infill panels which have in turn been covered with modern plastic paints. The timbers themselves have also been coated with plastic gloss paint. Together these paints and the render itself has trapped water in the timbers and the walls to induce the rot observed.

Based on the above closer inspection of all the timbers is vital and in particular on those that may indeed be carrying some part of the overall roof load. Attention should first be focused on the main vertical posts and the uppermost wall plates to verify their condition. Also to determine whether the inner masonry skin which I believe is not carried by the frame is sharing any weight load from the roofs timbers. Its likely that gravity will have helped to confine much of the damaging decay to the lower sections of the posts and the cill beams - these too must be closely inspected to assist determinations on how best to support the roof and the lower sections of the frame while repairs are made. Come what may all that render must be removed and the rotten timbers replaced. It may also be necessary to temporarily support the masonry of each of the infill panels while repairs are made to the supporting timbers below - hopefully however, the outer masonry skin is bonded into the internal wall to thus limit this need.

Once the frame has been repaired and the rotten timber replaced all the paint covering the timbers must be removed and the timbers treated with a breathable oil - linseed or tung. A lime mortar render coating should be applied to the masonry infills and this should ultimately only be painted with a breathable coating such as a limewash.

Good luck with this one, you have your work cut out for you but I'm glad to say I think it could have been a lot worse.

 

[CTid]

I don't want to give you any false hopes but I am seeing clues that suggest that some, perhaps many, elements of that timber frame are Not structural components of the house proper. Among the indicators are: -

1. The most obvious is the vertical timber that has already been removed as shown in the first photo.
2. In that first photo and the third it can be seen that two heavy screws have been a has been used to close the joint between the two horizontal members.
3. However, that corner post seems to have had some major surgery in the past to insert a new section of timber in the first circa 60cm. This kind of repair is often made to heavy timbers but in itself is not conclusive.
4. Immediately below that repair I can see what appears to be a cross headed heavy screw - confirmed in the third photo?. It would be unusual but that screw could have been used to fix a tenon blade from the new section of post inserted above but conceivably this may also suggest it was used to fix the cill timber to the tail of the post.
5. In the second photo the cill beam itself seems to be just circa 100mm thick. This would be unusual for a cill plate timber insofar that it implies it cannot be directly supporting the full load of the masonry infill walls above it. Do any of the timbers comprising the frame appear indoors?
6. The fourth photo seems to be of an odd feature of the framing insofar that the joint seems to include a mitered section connecting two horizontal timbers which in turn support a vertical post while the horizontals sit on what appears to be an outrigger from another horizontal timber that originates indoors. All of which appear to be fixed together with heavy screws.
7. The fifth photo confirms that a metered joint has been used at the junction of two horizontal timbers but again this joint is fixed with heavy screws. The placement of the screws also suggests, presuming they were driven in at an angle, that the timbers are not particularly thick - I'm guessing no more than 100mm.
8. In the sixth photo the corner post to the left has clearly been constructed in two parts using a lapped joint. Of itself this is not unusual but the pegs apparently used to wedge and lock the joint appear to be in the wrong positions.

Sadly the frame has been constructed of a softwood, pine almost certainly, and barring for the corner posts of the structure, I suspect that all the other timbers, with the exception perhaps of the cills, are no more than 100mm thick and some of them maybes as little 50mm. The builders, in using heavy steel screws, to fix many of the joints have contributed to the decay because steel and the woods tannins do not do well together - there is a good chance that many of the screws have corroded almost to nothing. Very clearly a cement based render has been used to coat the masonry infill panels which have in turn been covered with modern plastic paints. The timbers themselves have also been coated with plastic gloss paint. Together these paints and the render itself has trapped water in the timbers and the walls to induce the rot observed.

Based on the above closer inspection of all the timbers is vital and in particular on those that may indeed be carrying some part of the overall roof load. Attention should first be focused on the main vertical posts and the uppermost wall plates to verify their condition. Also to determine whether the inner masonry skin which I believe is not carried by the frame is sharing any weight load from the roofs timbers. Its likely that gravity will have helped to confine much of the damaging decay to the lower sections of the posts and the cill beams - these too must be closely inspected to assist determinations on how best to support the roof and the lower sections of the frame while repairs are made. Come what may all that render must be removed and the rotten timbers replaced. It may also be necessary to temporarily support the masonry of each of the infill panels while repairs are made to the supporting timbers below - hopefully however, the outer masonry skin is bonded into the internal wall to thus limit this need.

Once the frame has been repaired and the rotten timber replaced all the paint covering the timbers must be removed and the timbers treated with a breathable oil - linseed or tung. A lime mortar render coating should be applied to the masonry infills and this should ultimately only be painted with a breathable coating such as a limewash.

Good luck with this one, you have your work cut out for you but I'm glad to say I think it could have been a lot worse.

Thank you for your detailed reply. It seems like the timber is like you say not structural everywhere - we keep being told it’s a strange construction for the age of the house (1918).
I have no clue about any of this and have heard the term it’s only the ‘outer skin’ which I think is what you are saying here. There are no visible timbers internally no.
I have managed to find a timber specialist to come and have a look so I’m really hoping as you say it’s not as bad as it could have been. He also said he could do like render - just hope he comes through!

 

[Cubist]

There are some simple tests, albeit slightly intrusive but repairable, to confirm which of the timbers may have some structural role and those that are largely decorative. On the less intrusive side a good well experienced timber framer can discern the mass of a given timber with some judicious heavy taps with a mallet and judge whether it is badly decayed/rotten. In some locations though he or she may need to drill a few holes, with your permission, so determine the depth/thickness of the wood and establish what materials may be hidden behind them. He/she would typically plug such holes before leaving the site.

I would stress though that the key worry would be whether that frame is providing any degree of meaningful support to the roof structure.

 

[CTid]

There are some simple tests, albeit slightly intrusive but repairable, to confirm which of the timbers may have some structural role and those that are largely decorative. On the less intrusive side a good well experienced timber framer can discern the mass of a given timber with some judicious heavy taps with a mallet and judge whether it is badly decayed/rotten. In some locations though he or she may need to drill a few holes, with your permission, so determine the depth/thickness of the wood and establish what materials may be hidden behind them. He/she would typically plug such holes before leaving the site.

I would stress though that the key worry would be whether that frame is providing any degree of meaningful support to the roof structure.

Thank you - this was his reply when I sent pictures.

I can see what you mean now - the bricks sitting on the timber could possibly be just infill panels, they seem to not be carrying any weight from above but might possibly be toothed into the inner leaf brickwork but would have to take a bit more render off .



From what I can see from the pics is there's possibly some full pieces of timber to replace, however may possibly be that they could be repaired without removing the full sections altogether.



The render panels perimeters where they touch the timber are causing wood to rot but the centre of the panels look quite robust and if not falling apart or causing undue moisture build up inside the building could possibly be saved and just cut out the perimeters and replace with lime render.



I'd have to come and look closer my impression at the moment is that these could be like for like repairs and not load bearing for floors or roof, just carrying the facade - in other words it looks more like it could be approached more like a maintenance job than a structural renovation even though where contact between adjacent surfaces has deteriorated the timber is pretty extensive.

 

[Cubist]

Thats a more positive outlook and hopefully for the sake of the house he/she is right. One caveat though from my perspective - it is possible to remove say a narrow border of the render from the infills and replace it with a lime render but lime based and cement based mortars do not bond well together, this introduces a risk of hairline gaps between the two that would permit rainwater ingress behind the render to induce future damp and decay problems.

 

[malcolm]

I can see a lot of repairs in the photos. It was common for cement render to be used in the 1920s/1930s which isn't helpful, but the really important thing for external wood is not to waterproof it. You will always get water into gaps and joints so it is very important to let the water out again. I left the cement render on my infill panels but used linseed paint on the wood to make it breathable. What I should have done is added a layer of linseed oil on top of that as the pigment is dusting off and staining my limewash, but in any case the wood should end up with a very breathable coating or stain and only needs UV protection.

The frame is structural where there are bricks on top of it, and 'applied' where it is just stuck onto the face of the bricks. Applied timber is much easier to fix. For structural timbers you would need to support the bricks with acrow props while you replace the timber (or part of it). My bricks were held together in panels by the cement render so were easy to deal with.

My frame was quite good and I didn't write much about it. I found this: https://www.the-salutation.co.uk/blog/preparing-the-facade-for-paint/ Where you end up with a gap between the wood and render use lime mortar to fill the gap. I used linseed putty for smaller gaps.

Clearly there is timber replacement needed in yours. It would be good to use decent wood. Douglas Fir is probably the closest in quality to the slow grown pine originally used in the 1920s.

 

[CTid]

Thats a more positive outlook and hopefully for the sake of the house he/she is right. One caveat though from my perspective - it is possible to remove say a narrow border of the render from the infills and replace it with a lime render but lime based and cement based mortars do not bond well together, this introduces a risk of hairline gaps between the two that would permit rainwater ingress behind the render to induce future damp and decay problems.

Do you know how I would 100% ascertain the structural element and if anything is supporting the roof? I tried to get help from Building control but they just sent me links to RICs website. I’m unsure who is best to contact - a building surveyor or a structural engineer? I spoke to one structural engineer who said he didn’t know!

 

[CTid]

I can see a lot of repairs in the photos. It was common for cement render to be used in the 1920s/1930s which isn't helpful, but the really important thing for external wood is not to waterproof it. You will always get water into gaps and joints so it is very important to let the water out again. I left the cement render on my infill panels but used linseed paint on the wood to make it breathable. What I should have done is added a layer of linseed oil on top of that as the pigment is dusting off and staining my limewash, but in any case the wood should end up with a very breathable coating or stain and only needs UV protection.

The frame is structural where there are bricks on top of it, and 'applied' where it is just stuck onto the face of the bricks. Applied timber is much easier to fix. For structural timbers you would need to support the bricks with acrow props while you replace the timber (or part of it). My bricks were held together in panels by the cement render so were easy to deal with.

My frame was quite good and I didn't write much about it. I found this: https://www.the-salutation.co.uk/blog/preparing-the-facade-for-paint/ Where you end up with a gap between the wood and render use lime mortar to fill the gap. I used linseed putty for smaller gaps.

Clearly there is timber replacement needed in yours. It would be good to use decent wood. Douglas Fir is probably the closest in quality to the slow grown pine originally used in the 1920s.

Thank you. Don’t think we would have bought the house had we known all this. We had a fully survey and when we found out about the structural element I went back to check it and it said ‘the mock Tudor cladding is unlikely to be structural’. I get the impression that over half of it is structural and the other not.

 

[Bogart]

Structural engineer or surveyor? You problem is you want someone who has experience of similar buildings. Is yours a one off or are there others similar nearby? No point in having a strucutral engineer around unless he knows about old building methods, most do not. A surveyor might know how it was built but not neccessarily how to repair, or what even needs repairing.
As far as I recall quite a few timber frame buildings in Cheshire, maybe knock on a few doors.

 

[montyjohn]

Thank you. Don’t think we would have bought the house had we known all this. We had a fully survey and when we found out about the structural element I went back to check it and it said ‘the mock Tudor cladding is unlikely to be structural’. I get the impression that over half of it is structural and the other not.

Why do you think some of the timber is structural? It's hard to tell from the photos, but I could imagine any overhangs would be, but all the timber on flat faces seems to be a cladding only.
The way the paint is peeling from the render and timber is a real shame.
I would have thought having it shot blasted would be the first step and see what you are left with.

 

[Cubist]

Do you know how I would 100% ascertain the structural element and if anything is supporting the roof? I tried to get help from Building control but they just sent me links to RICs website. I’m unsure who is best to contact - a building surveyor or a structural engineer? I spoke to one structural engineer who said he didn’t know!

You could check in the loft to see if the roofs rafters are directly carried on any of the uppermost external beams or perhaps on brickwork laid directly on top of those beams. Short of that you are in the hands of a structural surveyor or you could merely trust the chap you have already been speaking to who seems to have a good idea what he may be dealing with. If you are in any doubt about what you're told come back here with your questions and we will try to help.

One other thing to mention here though - do not under any circumstances consider 'shot blasting'. Soft media blasting MAY be appropriate in the hands of a skilled and assiduous technician, but even then there is a risk of considerable collateral damage. Shot blasting uses thousands of tiny steel balls to erode the unwanted materials and is capable of turning a house brick into a cloud of dust in just a few seconds.

 

[CTid]

You could check in the loft to see if the roofs rafters are directly carried on any of the uppermost external beams or perhaps on brickwork laid directly on top of those beams. Short of that you are in the hands of a structural surveyor or you could merely trust the chap you have already been speaking to who seems to have a good idea what he may be dealing with. If you are in any doubt about what you're told come back here with your questions and we will try to help.

One other thing to mention here though - do not under any circumstances consider 'shot blasting'. Soft media blasting MAY be appropriate in the hands of a skilled and assiduous technician, but even then there is a risk of considerable collateral damage. Shot blasting uses thousands of tiny steel balls to erode the unwanted materials and is capable of turning a house brick into a cloud of dust in just a few seconds.

Thanks so much. I have been trying structural engineers and surveyors for a while and still unable to find anyone who knows or has any experience in this particular thing. I do have a good builder who we have used and family have used so he may be able to look in theory for me. I have necessary heard of shot blasting - what would someone use thst
For? Paint removal do you mean?

 

[Cubist]

To be clear; shot blasting would be completely inappropriate for use around your house. It uses high pressure air to fire small steel balls at a very hard surface such as steel to remove heavy deposits of rust or to burnish the material as part of preparation for paint. It is far too aggressive for your needs and would literally tear that wooden frame of yours to pieces. Media blasting uses softer materials such as dry ice and lower air pressures to remove old paint and unsightly stains from heavy timbers BUT even this can literally shred rotten or softer woods like pine.

 

[CTid]

To be clear; shot blasting would be completely inappropriate for use around your house. It uses high pressure air to fire small steel balls at a very hard surface such as steel to remove heavy deposits of rust or to burnish the material as part of preparation for paint. It is far too aggressive for your needs and would literally tear that wooden frame of yours to pieces. Media blasting uses softer materials such as dry ice and lower air pressures to remove old paint and unsightly stains from heavy timbers BUT even this can literally shred rotten or softer woods like pine.

Thank you - it was suggested the paint would be ‘burnt’ off?

 

[Cubist]

Hot-air guns or gas blow-torches are commonly used to strip paint. There no risk to the house if used properly.

 

[a twig]

I’ve got an older one of these which has been great for these jobs

IR Paint Stripper

The IR Paint Stripper is a new tool that safely and effectively strips paint. Exclusive to Brewers, the paint stripping tool uses infra red technology to separate the bond between paint and substrate, allowing you to remove layers of paint with ease. Simply place the IR Paint Stripper's ceramic...

www.brewers.co.uk

 

[Cubist]

I’ve got an older one of these which has been great for these jobs

IR Paint Stripper

The IR Paint Stripper is a new tool that safely and effectively strips paint. Exclusive to Brewers, the paint stripping tool uses infra red technology to separate the bond between paint and substrate, allowing you to remove layers of paint with ease. Simply place the IR Paint Stripper's ceramic...

www.brewers.co.uk

Coo, new toy.... nearly made it onto my Crimbo list until the First Lady said "You do recall that after stripping the old you get to apply the new?" - bah humbug.

 

[LadyArowana]

- do not under any circumstances consider 'shot blasting'.

And if anyone is wondering why they might have heard of this in relation to a house refurbishment it’s what gets done to Agas or any other sort of old range when you want to change the colour. The first process is to remove the old enamel from the panels.

 

[Cubist]

And if anyone is wondering why they might have heard of this in relation to a house refurbishment it’s what gets done to Agas or any other sort of old range when you want to change the colour. The first process is to remove the old enamel from the panels.

Also extensively used by local farmers round here for application to the backsides of poachers with the aid of a Double Barrelled Browning - lead not steel shot though.