Replacing Structural Timbers

[Charollaise]

I’ve several DIY renovations/conversions behind me (own homes) and recently bought a three storey plus cellar, terraced town house to become my own flat, plus give me work/income possibilities. With the help of a friend with similar experience (but more effective muscles than my middle-aged girly ones!) we’ve been carefully removing all the awful additions, ready to start re-constructing from early next year. Absolutely everything needs doing, apart from the roof which is ‘new’, and the stone walls are more or less vertical! (it dates from 19th, 17th and 15th century so a bit of quirkiness is to be expected and is even welcomed!)

Nothing much scares me. Not really. I have a healthy respect for practical things and not being stupid – though that’s a bit of a subjective concept I know! All is possible when you know how, or at least find out who to ask, and what to use.

Which brings me to the interesting new-to-me challenge I’m now faced with and would appreciate serious advice please. S’ok – don’t mind the daft comments too (as long as they’re entertaining) – you won’t come up with anything I haven’t already heard – trust me!!

Within the stone, there’s a lot of structural timberwork – A-frame? with floor/ceiling beams running 5 metres front to back at each level and every couple of metres side to side. Imagine the double fronted property split into thirds with a wide staircase in the middle and single room spaces either side. It’s built mostly (but not entirely) up against the stone battlement walls of a long demolished castle.

I need to find out how (Step by Step Guide please?) to replace all the timbers running along the back wall to the right hand side of the central stairwell and about a metre +/- into the rooms at each level at the corners. That’s ground floor ceiling/first floor floor, and first floor ceiling/second floor floor…

Amazingly there was little visible sagging. Around 2cms at first floor skirting along about 5 metres. Was when we pulled down a damaged lathe and plaster ceiling and started looking at the inter-floor/ceiling space along that back wall we realised it does all have to be done. The worst of the wet rotted timbers are in fact against a bit of exterior wall that isn’t against the battlements.

As a precaution, we’ve installed a couple of Arco props in the corner at ground level, but they’re not really doing anything. The house would appear to be extraordinarily self-supporting (currently!!!) even though the wood resembles nicely crumbled earth in too many places!

I have a trustworthy local wood-man, who will happily supply me with reasonably priced oak… or am happy to go the I beam/RSJ route if that’s better/easier/more practical… as most will not remain visible.

To head off one likely specific question in case anyone’s wondering – they really don’t “do” surveys here and in any case it wouldn’t have made a ha’pennyworth of difference to my choice to buy – the purchase price really did reflect the work I need to do and it’s going to be one hell of a place when it’s done. And I don’t mind hard work one jot… not like the locals – I love them dearly, but they’re sensitive souls who do scare easily and give the sharp intake of breath (and associated price hike) when opinions asked – which is why I’ve come to Brits who I know I can trust to provide a range of ideas and solutions and maybe some comedy to boot. We are eminently capable of physically doing the work – when we know what to do.

Please fire away with any questions to help clarify anything if you need, before you answer – is really hard to know what/how much to describe. Haven’t a clue how to post photos though… happy to learn if it’s not too hard/time consuming! Thanks a lot, in cheerful anticipation.

 

[RigidRaider]

I have lived in France for over three years so I do know that Calvados is excellent for house restoration. You have to drink it first then you begin to think like a true Frenchman, shrug your shoulders and say things like "Quoi? Bof! Je m'en fous!"

 

[A1chippy]

sounds like a nightmare but i would remove all rotten timber in the walls and replace brick or stone and sand and cement it all in to make walls good

 

[gregers]

i wouldve thought that these timbers are more likely morticed/tenoned and pegged,you obviously must also be aware that when the timbers are removed the wall will drop?
im no expert with building as such,im just a humble chippy but have done a few jobs that have been very similar in the make up as yours.

also be prepared for dry rot.

hope youve got long arms and short pockets.

 

[Charollaise]

Thanks for replies so far!

I'm dangerous on a single glass of red - though Calvados... peut-être ça me ferait du bien?!

Removing/replacing the timbers is what I had in mind but because they provide support for the floors they'll need to be replaced with something similar. Neat idea if that wasn't the case.

Interestingly they're not morticed/tenoned, but laid one on top of another! (up in the roof's a different story - but they're all perfectly sound) Makes life a whole lot 'easier'. The wood's so crumbly in places that individually the timbers aren't doing much holding up job at all - rather thankfully them interleaving with each other is providing sufficient collective strength which leads me to believe that they only support the floors/ceilings rather than the walls.

I woke up this morning with this thought and feel it might work...what does anyone think?

Measure accurately the replacement required in each case, and starting with the lowest one (?) slide it into place whilst scraping out the rotten timber ahead of it. Can access from the floors which are safe to walk on, or the scaffolding tower underneath. Using the Arco props/timber planking under joists at each level.

I'm more than happy to chuck ideas about here and go for the one that sounds most logical - like I said I don't scare easily and am always thinking "What's the worst that could happen?" Usually my answer to that brings a sense of calm rather than fright!

Haven't discovered dry rot in anything we've uncovered - which is a considerable amount, just wet .... and worm!

 

[RigidRaider]

My not be significant but if you opt for some kind of replacement as you describe, be sure to use timber that's well seasoned. If the building is fundamentally damp the timber might swell a little, giving a tighter fit into the brickwork. Just a thought.

 

[mointainwalker]

I am not sure I am absolutely clear, but if I have understood you are simply worried about floor-joists - right ?

Given the age and likely construction methods I think it unlikely that the joists are part of the integral structure.

To firm up on this I would talk to other people who have renovated.

Are you in an area where there are lots of Brit or Dutch renovators as this will let you tap into a lot of experience.

I also find it hard to believe there isn;t some old boy around who is not willing to tell you of his years' of experience with the local artisans as a mason/carpenter whatever. Somebody like that would be invaluable for knowlwdge as well as giving you good leads on where to source materials.

Depending on what you learn, I would then carefully dismantle/demolish a small part of the joists to see how they fit into the walls and if you can safely deduce that they just hold up the floor.

I don't think you will be able to buy seasoned wood for joists unless you are willing to spend an absolute fortune and I don't believe it is necessary.

I live in the Alps and all houses are done with green-wood: being the Alps this includes plenty of purlins 10 m x 400 x 400 for example to fit in with the vernacular and although they crack they very seldom warp.

When ordering from the saw-mill, tell them you want "qualite charpente" and for a small extra cost you will get wood cut from parts of the tree that will be more stable.

My experience was that of 56 joists 3.2 m x 140 x 140 in spruce, I only had one that twisted badly and I had to plane down to allow flooring to lay level.

Apart from that there are plenty of cracks as the wood has dried but that's to be expected.

Can't comment on your wet walls other than to say tear off all plaster /coverings etc to allow it to dry out as much as possible and then take a view if it's the gutters/walls etc .

Somebody suggested using cement/concrete which is, I believe, totally wrong. Old buildings like this were built with lime and this is a more flexible material which suits an old structure where nothing is square or level. Cement is also an ugly grey which leaves hideous "scars" on old walls if it visible.

Lime is still in common usage in France.

Let us know what you find/decide.

 

[Charollaise]

Thanks very much mointainwalker, am pretty sure now it is only floor joists I'm concerned about, be they the ones spanning the 'open' space, or the ones running along/set into the walls supporting those. My DIY/'builder' chap and I have been carefully dismantling and revealing what's in the corners specifically, and it certainly appears as though this is the case.

Unfortunately in some ways - I'm the only one who's renovated to this level that I know of - everyone thinks I'm nuts! I will certainly start asking around locally to see if anyone wants to talk to me. Bit of a typically French patriarchal society though....

Sourcing materials not a problem, I've a previously well used and trusted man at his timber yard (supplied all the oak for the last house's barn opening/doors and for a passarelle I designed spanning the mezzanines across double height barn living space). I would be quite happy to use a treated steel I-beam for the one along the stone wall supporting the others, as it's this one that's going to be subjected mostly to the damp.

The gutters are relatively new and fine - one of the delights of the house being built against the castle battlements is that it's possible to go up onto the public garden on top and view my roof - and gutters, from above!

Interestingly it would seem that the worst of the damp is actually along the point of 'exterior' wall where the house isn't joined to the battlements. Though the rear wall and a metre section inwards of the central section containing the stairwell has been cement rendered.

The old lime render elsewhere is falling off in places and I either will remove completely and lime-point the stonework, (as on last house) or completely lime render again.

I wish I knew how to post images/diagrams on here - is it difficult? It would be much easier to understand what I'm trying to say - don't feel I'm doing too good a job of explaining!

 

[RigidRaider]

It's easy enough to post pictures. Set your camera to a smallish size, say around 2 mp. Join a picture hosting site like Photobucket. Upload the pictures to Photobucket using the browse feature and finding them on your computer. Then you'll find a drop-down menu under each of the pics in your album, the second of which will be the direct link address. Left click on this and it will be automatically copied to your mouse. Then write your post here on DIYnot.com and where you want the picture to appear, paste that link into the text. You then need to tell DIYnot.com that the link is a picture so you need to enclose the link you pasted with square brackets and a small code:

at the end, no gaps. DIYnot.com will then go off and get the picture from Photobucket where it is hosted on the web.

 

[Charollaise]

Thanks very much for that Rigidraider... I'll try and suss it out over Christmas... am brain-dead this time of night for anything remotely technical!

More thoughts from today's work at the house...

The inner skin that's been created inside the rear wall really hasn't done the timberwork any favours at all. Admittedly it's created a cavity and will mean that the house is better insulated, but to permanently incarcerate wood like that seems like it was asking for trouble. So... tomorrow's job is to remove all that terracotta blockwork and see what we've got. Replace the rotten wood with either timber or steel, then re-do the first floor inner skin in 100mm polystyrene faced plasterboard, battened/spaced (probably) with aluminium. (used to good effect in the last house) The second floor I'm probably happy to remove what's left of any lime render and lime point the exposed stonework. Is the really pretty golden pierre dorée.

If nothing else... the massive reduction in weight on everything has to be a good thing!!!

The exterior of the stone wall (not attached to the battlements) was cement rendered at some 'recent' time, again not a good idea... but not a lot I can do about that - is - sadly - perfectly sound!

 

[mointainwalker]

You can also upload piccies via the DIY system which is a bit of a buggeration and don't know if photobucket is better/worse.

Click on "Help " at top of page.
At bottom of next page , under "Formatting" the last line is "upload Images" or similar.
Click that and in the first line click on "here" and you should be the beginning of an exasperating process.

That apart, i'm a bit surprised that the tone of your posts seem to imply that you are going to accept having a wet wall - surely not ?

The standard practice for joists going into walls is to wrap the ends ( and at least 20 cms (?) inside wall ) in heavy polythene such as DPM and staple to joist to keep water-free.

The insulation value as a cavity isn't huge. Its main purpose was for weather-proofing.

 

[ladylola]

I woke up this morning with this thought and feel it might work...what does anyone think?

Measure accurately the replacement required in each case, and starting with the lowest one (?) slide it into place whilst scraping out the rotten timber ahead of it. Can access from the floors which are safe to walk on, or the scaffolding tower underneath. Using the Arco props/timber planking under joists at each level.

If I'm reading this right it sounds a brilliant plan , sliding one in as the other is scrapped out in front but it has only one minor flaw- it won't work.
I work in restoration and have done this type of thing and you have a couple of options really. Firstly whatever you do support the floor joists with acrows. Then remove all the decayed timber and you may consider spraying the exposed stonework with some sort of water based treatment. The hole you have now created can now be either filled in with masonary or if you prefer timber. The timber will need to be positioned along the wall so that it can be lifted and pushed into place. The fit will not be perfect , you will find that you need to remove (if it hasn't dropped out) some material from above or below the timber. When the timber is in position it can be built in making sure to press home the mortar and pack with slate to ensure the joints remain tight.
As already said we want/need pictures

 

[Charollaise]

omg... today's interesting discoveries... nothing's fallen down yet so that's a bonus!


I removed bathroom inner wall, no problems - large timber along wall much better condition further away from the corner. Brilliant. Part way through doing bedroom, went to knock what I thought was a bit of blown plaster off the wall behind and hammer went straight through an on-its-side brick... Shining torch through the neat round hole, and I realised there's another wall half a meter further back again!!! Gingerly scraping plaster off, and then lifting off bricks one by one (they didn't need hammering!) has revealed a stone alcove almost as if it may have been an opening at some point historically... who knows! (diabolical view but - battlements only a few feet away!) Have to say the old heart did a bit of a flutter when the thought of skeletons flashed across my mind!!!

Great feature... but messed up my plans for having the wall-to-wall wardrobes along that wall!!

Photos... blugh! Sorry guys - really is a technicality too far for me this time of night - bit like algebra - I have my limitations! I'll have a crack during daylight hours when not working at the house...

Am glad it sounded like a brilliant plan at least! Everything's well supported with acrows - ground to first, and first to second. Is all solid and there's no movement at all.

Sounds simple enough to wrap ends in polythene which I can do for any new wood going in, but the rotten ends of otherwise saveable ones, I was wondering about making long enough (treated) steel 'collars' (have access to cutting and welding gear) to slide over the cut-back ends, joists offered up and collar slid into the wall... whaddya reckon?!

The more I'm uncovering, the more I realise that most of the hefty timbers along the walls actually only sit on each other rather than are set into the stonework - the amount of 'material' dropping down from behind when I've been banging is a bit of a giveaway!

Not sure about how much damp is acceptable or not... the alcove that's been revealed is jolly damp inside - some of those bricks that came out literally crumbled in my hands. Not sure why it would be so wet. Is first floor, so well above the height of rising damp - and in any case the ground floor appears to be ok. The roof and guttering are fine, the external rendering's not compromised, and the second floor stone wall immediately above isn't damp. Might it just be the fact that it's all been sealed up that's caused the problem - and that ventilating it will eventually remedy?

Like I say - am happy to keep chucking ideas into the pot (even my duff ones!) and am very glad of all your input - I appreciate it enormously - thanks!