New lintel/flat roof issues

[Cassie]

Oh dear, it turns out that the very rotten timber between my porch and hall is actually what is holding up the two floors above. Clearly needs replacing. Quoted £2900 +vat. Ouch. This of course doesn’t address the cause of the rot which appears to be a drain problem with the parapet roof above. Suggested fixes were paint the roof and parapet with rubber seal paint (£1190 +vat!!) or strip off existing covering, redo with fibreglass and put lead where it should be around the drain (£5400 +vat ).
There seems to be little point in replacing the lintel if the cause isn’t solved but having checked down the back of the sofa, I don’t have the cash! I’ll get some more quotes first off, although the lintel issue is worrying me somewhat. I wouldn’t pay someone else to paint the roof, I’d do that myself, but I fear it’s just throwing away money and won’t solve the problem long term. It may give me time to save up though, but by then, the second lintel will probably have rotted. Sigh. Any thoughts? Cheers!

 

[Cubist]

Ouch indeed. Your priorities are in the right order better to get the lintel replaced first and I would suggest a steel one rather than more timber. Sadly, while this is a job that some adventurous souls will have a go at there are other considerations in terms of safety and insurance liability that need to be taken into account. The normal method is to use several acrow-props and associated supports to take the weight of the brickwork above the existing lintel before it is removed and the new one installed, The props and supports need to be carefully positioned to avoid any risk of collapse while leaving sufficient space to manoeuvre the new lintel into place. Not a job for the feint hearted and made more difficult/dangerous if working at height. Sorry but I think this one may be the one for discretion rather than valour.

P.S. If you do decided to hire someone make sure they provide proof of insurance cover for your house while undertaking the work.

 

[Cassie]

Thanks cubist. I too feel that this is definitely one for an experienced and insured professional. Acro props were mentioned, but I’m not entirely convinced that the wooden steps leading up to the hall are up to taking the weight of the house. I have in fact just asked a structural engineer to come and take a look- a few quid now could save a lot of trouble later! Once I hear their advice I’ll be more armed to ensure I get someone capable in. Better stock up on baked beans, I fear this is going to be very costly

 

[Cubist]

Acro props were mentioned, but I’m not entirely convinced that the wooden steps leading up to the hall are up to taking the weight of the house

Ugh, wooden steps/weight of house - unlikely . APs are available in a range of sizes up to 5 metres fully extended but will rely on a solid base almost directly below the lintel and position of the bases will depend on which way the old/new lintel has to be taken out/installed. Hopefully there will be other options than taking out the steps. Good luck.

 

[Cassie]

Thanks cubist. I’m feeling a bit down in the dumps about it I’m also a bit scared that it’s suddenly going to fail catastrophically (I know this is unlikely, but not impossible!) it’s definitely better to know though in this case, before I install a bath above it-catastrophic failure would be embarrassing if I were having a soak at the time!

 

[Feltwell]

Ouch! Worth getting more than one quote. Replacing a bressumer isn't particularly a conservation-specific builder job. As above, I'd put a steel in rather than replace with timber, you'll need the structural engineer to do the calcs for that anyway. May well need Building Control to be notified.

The wall above would usually be supported on Acros and Needles (basically lumps of timber driven through holes in the wall, at 90 degrees to & above your rotten lintel/bressumer) or Acros and Strongboys (like a bracket that goes on the top of an Acro with a flat steel plate that sticks into your brickwork).

The acros do need to be on a solid base, if they have to sit on a suspended floor then getting underneath that floor and putting further props below it down to solid ground beneath is an option.

Nearly £3k sounds like a lot, but of course we can't see all of what it entails.

 

[Feltwell]

Thanks cubist. I’m feeling a bit down in the dumps about it I’m also a bit scared that it’s suddenly going to fail catastrophically (I know this is unlikely, but not impossible!) it’s definitely better to know though in this case, before I install a bath above it-catastrophic failure would be embarrassing if I were having a soak at the time!

Very unlikely, and brickwork above an opening will only fail in a triangular shaped zone. Google "self-corbeling" and you'll see what I mean.

 

[Cassie]

Ouch! Worth getting more than one quote. Replacing a bressumer isn't particularly a conservation-specific builder job. As above, I'd put a steel in rather than replace with timber, you'll need the structural engineer to do the calcs for that anyway. May well need Building Control to be notified.

The wall above would usually be supported on Acros and Needles (basically lumps of timber driven through holes in the wall, at 90 degrees to & above your rotten lintel/bressumer) or Acros and Strongboys (like a bracket that goes on the top of an Acro with a flat steel plate that sticks into your brickwork).

The acros do need to be on a solid base, if they have to sit on a suspended floor then getting underneath that floor and putting further props below it down to solid ground beneath is an option.

Nearly £3k sounds like a lot, but of course we can't see all of what it entails.

Thanks feltwell. I really don’t know how they would do it-the walls are a bit dicey as it is. Underneath is a boiler room with a wall between it and the house, so propping up from below probably not possible. I don’t know what’s under the steps (but it’s bound to be something that doesn’t help!) I’m not going to do anything else until SE has been- I’ll ask him to do calculations for steel, then I’ll start trying to find builders to quote. Of course I’ll need to add on the cost of roof repairs as well. It might be that’s just what it costs-I’ll start booking in the overtime now!

 

[Cassie]

Very unlikely, and brickwork above an opening will only fail in a triangular shaped zone. Google "self-corbeling" and you'll see what I mean.

I’ve just looked it up-I did not know that! Reassuring, but I’m still only going in there very gingerly

 

[Cubist]

Just make sure you dont hire this builder.
The Bricklayer's Lament - by Gerard Hoffnung - YouTube

 

[Cassie]

Just make sure you dont hire this builder.
The Bricklayer's Lament - by Gerard Hoffnung - YouTube

Thanks for cheering me up Cubist!

 

[stuart45]

There are other options to propping a wall when acros aren't practical. Steel plates on each side of the wall, bolted together have been used. There are some devices like No more props that have been developed on that method.

 

[Cubist]

There are other options to propping a wall when acros aren't practical. Steel plates on each side of the wall, bolted together have been used. There are some devices like No more props that have been developed on that method.

Coo, new toys. These look interesting and so do the Brick Brace kits - bit pricey but they look capable.

 

[malcolm]

I have in fact just asked a structural engineer to come and take a look- a few quid now could save a lot of trouble later!

I was there at the start through lack of confidence. I found it a complete waste of money and have never had one of them back despite doing some more structurally challenging jobs later on. They are only good for doing official sums to make building regs happy.

Without pictures I'll guess it is a rotten softwood lintel. Replacing it with anything will be stronger. Steel and concrete are more dimensionally stable than wood and I tend to lean towards concrete when I'm doing this sort of thing.

Don't get too worried about the house falling down during replacement. As Feltwell says it's only a very small part of the house at risk of falling down, and it doesn't need a lot of support to keep even that bit sound. Props are only taking the same sort of weight as a human and you don't screw them so tight. A decent builder will have done dozens of these jobs. A few bricks will come loose above the lintel and you'll have to sort them once the new lintel is in. If it's a general builder that's your job as they don't tend to like lime.

 

[stuart45]

What's the opening span?

 

[Cassie]

I was there at the start through lack of confidence. I found it a complete waste of money and have never had one of them back despite doing some more structurally challenging jobs later on. They are only good for doing official sums to make building regs happy.

Without pictures I'll guess it is a rotten softwood lintel. Replacing it with anything will be stronger. Steel and concrete are more dimensionally stable than wood and I tend to lean towards concrete when I'm doing this sort of thing.

Don't get too worried about the house falling down during replacement. As Feltwell says it's only a very small part of the house at risk of falling down, and it doesn't need a lot of support to keep even that bit sound. Props are only taking the same sort of weight as a human and you don't screw them so tight. A decent builder will have done dozens of these jobs. A few bricks will come loose above the lintel and you'll have to sort them once the new lintel is in. If it's a general builder that's your job as they don't tend to like lime.

Thanks Malcolm-I’m definitely lacking confidence, probably for good reason! Maybe I’ll get braver in the future Being 5’2” and a bit weedy doesn’t help either, but at my age, I’ll be shrinking rather than growing

 

[Cassie]

What's the opening span?

Hi Stuart, it’s about 6’6”

 

[stuart45]

You would need a 2100mm lintel for that span. You could use a couple of concrete lintels, a couple of steels or a catnic. Concrete are the heaviest, but cheaper, catnic would probably be around £300. Manufacturers will always advise you on which lintel to use. With a lintel it also depends on whether it is taking any point loads.

 

[Cassie]

Forgive my ignorance Stuart, what do you mean by point loads?
To slightly complicate matters, I suspect it’s actually 2 lintels, one behind the other-possibly one for the house wall, which I can’t see properly, and one for the parapet wall on the porch roof? On the hall side, the area above the door is plastered on brick- perhaps I should take off the plaster and see what’s behind? Presumably the lintel wouldn’t be inside the bricks and therefore not visible??

 

[Cassie]

And on the subject of choice of lintels, which would be the best choice to withstand and future damp issues?!