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DIY ceiling query


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My bedroom has old timber beams in the ceiling but for some reason they were covered up by horrible old chipboard that was rotten due to a water leak and mouse piss. :CryBaby:

I decided to expose the beams and put plasterboard above them, screw the plasterboard on to the beams, and then get new Celotex type insulation above that (previously it was that horrible fibreglass stuff that mice love). 

The only problem is whenever I need to go into the attic I've been using crawl boards balanced on the old beams. But now the Celotex and plasterboard will be what I'm leaning the crawlboards on... 

Will this lead to loads of movement? the timber beams are old and have a bit of give in them. I was going to just use gyprock and scrim below to seal the plasterboard joints but now I'm worried that the amount of movement from above will cause the joins to break... any one got any ideas? 

PS plasterboard not fixed in yet.

 

From below

IMG_20201011_113109.jpg

From above in attic

 

IMG_20201011_113126.jpg

Edited by spunko
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You can  get a foaming adhesive that has slow expansion that is primarily marketed for a replacement for dot and dab plaster boarding. Reckon  spot gluing the celotex to the back of the board making sure you bridge the joins will do the trick - will stiffen up the whole lot. Don't glue to existing roof work in case you ever need to remove, just face to face plasterboard to insularion. Will  want to use a few plasterboard screws into the back of the beams, probably won't need to got overkill as you will pretty much make a single sheet but doing the glueing. Some decent length crawl boards over the top spanning least two beams in each direction think you will be fine, the bonded insulation/plasterboard itself will act as a load spreader. You'd need put weight on the insulation whilst the expanding foam was going off.

 

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Scrimming, maybe use frame sealant between the board edges to bond them together a bit and give them some flex resistance and then taped scrim. You cannot paper or mesh scrim tape, normally if just jointing paper is easier as thinner coat needed, mesh tape should be a little more soli but will use up a fair bit more jointing material. There might be some jointing compound brans out there that are a little more movement forgiving, not sure. Think would be more likely to crack and cause problems with movement if you did go traditional plaster. 

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Is it a detached property? If your loft floor is bouncing you might consider having RSJs installed below to support this mass of very old timbers; you ideally want no movement in your roof space at all. After installation, you can box them in to look like beams

If this is a terraced property, RSJs are exponentially more difficult, particularly if you break through to your neighbour's property when installing them.

WTH is happening in the gable end with those wicky-wonky timbers? They look like they were jammed in to support something, but only supported by a questionable roof space in the first place. Also, I see zero tie beams up there (the cross bar on a letter 'A') like someone once thought they might start a loft conversion then gave up after taking the cross supports out. This could be a recipe for disaster if the roof beams decide one day to splay open like a cheerleader doing the splits.

That one vertical timber on the left, that is supported only by the questionable floor joists and will fold like a card table if the roof starts to spread open. The pertinent questions: what is tying the roof beams together, what is preventing woodworm (bark left on beams is like a woodworm condominium) and what is supporting a loft floor (lower room ceiling) already under significant strain.

Sorry to be the bearer of so much bad news. I am a stickler for sound structure.

Edited by Conniption
I'm not a builder, I just play one on TV. And I own a five hundred year-old building.
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1 minute ago, Conniption said:

Is it a detached property? If your loft floor is bouncing you might consider having RSJs installed below to support this mass of very old timbers; you ideally want no movement in your roof space at all. After installation, you can box them in to look like beams

If this is a terraced property, RSJs are exponentially more difficult, particularly if you break through to your neighbour's property.

WTH is happening in the gable end with those wicky-wonky timbers? They look like they were jammed in to support something, but only supported by a questionable roof space in the first place. Also, I see zero tie beams up there (the cross bar on a letter 'A') like someone once thought they might start a loft conversion then gave up after take the cross supports out. This could be a recipe for disaster if the roof beams decide one day to splay open like a cheerleader doing the splits.

That one vertical timber on the left, that is supported only by the questionable floor and will fold like a card table if the roof starts to spread open. The pertinent questions: what is tying the roof beams together, what is preventing woodworm (bark left on beams is like a woodworm condominium) and what is supporting a loft floor (lower room ceiling) already under significant strain.

Sorry to be the bearer of so much bad news. I am a stickler for sound structure.

Looks like a sagging ridge lines been supported some stage.

I think in this case best to not touch the structure and make "cosmetic" changes only, ones that can be reversed just in case.

May look horrible but the wood is hundreds of years old and so long as not perforated with woodworm or rot is probably very strong, just not your regularised timber and moved over its lifetime up there.

 

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There was some woodworm when I moved in but had it treated and every spring there are less of them. I'm hoping now that I've exposed more timbers they will dry out more.

There's also a huge old chimney stack, just to the left of the photo in the middle of my house, I'm told it has original brickwork and masonry eg wattle and daub ,vwhich supports the entire house timbers. that's why there's no cross beam here in this room but the larger rooms have proper bressumer (?) beams.  in fact to the left of the first photo you can see the old one that is holding up my bedroom. The construction of this house I'm constantly being told by tradesman is different to anything anyone has ever seen, generally meant in a bad way I suspect. xD

PS My house is as old as yours @Conniption but my reasoning is the timbers have been there for 500 years so I would be very unlucky if they did collapse now.

Edited by spunko
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1 hour ago, onlyme said:

You can  get a foaming adhesive that has slow expansion that is primarily marketed for a replacement for dot and dab plaster boarding. Reckon  spot gluing the celotex to the back of the board making sure you bridge the joins will do the trick - will stiffen up the whole lot. Don't glue to existing roof work in case you ever need to remove, just face to face plasterboard to insularion. Will  want to use a few plasterboard screws into the back of the beams, probably won't need to got overkill as you will pretty much make a single sheet but doing the glueing. Some decent length crawl boards over the top spanning least two beams in each direction think you will be fine, the bonded insulation/plasterboard itself will act as a load spreader. You'd need put weight on the insulation whilst the expanding foam was going off.

 

Thanks. Just one other idea my mate had, do you think ditching the plasterboard altogether and putting loft boards down then Celotex insulation on top would be better? (stronger). The thinking being that plasterboard has no flexibility really so could break in half if buckled enough. 

Loft boards being that weird cork chipboard might bend a little.

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It would be stronger, all screwed together onto the beams would be pretty strong. Issue then is you have the chipboard to cover -you'll pretty much then have to over clad that with plasterboard get a decent finish on it from underneath in-between the beams. As alternative I suppose you could use something like lining paper but you already have the plasterboard so might as well use that. 

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Roughly what dimension are those timbers in the first picture? It might be perspective but they look wrong in proportion to the span suggesting they're not really beams or joists so much as ties to stop the roof spreading or a later addition to fix the ceiling to.

If the 'beams' are moving, I would suggest halving their span with a big beam across them in the middle, a hefty lump of oak I guess would be appropriate if logistically possible. Then with a solid structure in place and as suggested a chipboard floor upstairs, although the span between the 'beams' looks like it might be pushing it for the load bearing capabilities of chipboard, in which case you are looking at a layer of joists under the chipboard, even if they are only 2" x 4". In that eventuality the upside would be having straight modern 2" x 4"s to and the appropriate depth to  lay 4" cellotex between without gaps.

Regarding plastering the ceiling, personally I would do lathe and plaster between the timbers as it is an historic house. In my limited experience of interior work on timber framed or cruck + masonry type buildings, using plaster board between old timbers always ends up looking shit because seasonal movement cracks the skim, especially where scrim tape has been used to make up gaps along wonky edge old timber. Don't be afraid of having a go at traditional building  methods with lime plaster and so on, there's above average amounts of bullshit and mystique surrounding what were really simple techniques performed by unskilled or semi skilled labour using whatever materials were locally available. Just use clean sand and hydraulic lime as plaster, sharp sand produces a lovely coarse finish which looks great after a few layers of emulsion and is much more stylistically appropriate if the house is of a rustic nature.

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@Caravan Monster

The cross beams are i was told by someone supposedly knowledgeable on these things that they're supporting the roof. Here's a photo, they are nailed into the timbers going diagonally up.

Varied dimensions but about 6cm on average each side. they go E to W whereas on the other floors the thicker beams go N to S, which is strange. 

Worth adding I have a very shallow width house, it's almost like a ship from the side, and I wonder if this explains the roof setup.

16024263061413924328225952084531.jpg

 

I haven't really explained it very well. These beams are the A part that you referred to, @Conniption. My house has sunk so they've raised the internal floors up. Think of it like this, and it'll be easier to understand: the first floor is effectively a half first floor and half attic. The attic space has been reduced so as to fit into the first floor, as the house has sunk so much (and people were of course smaller too). 

 

@Caravan Monster I agree with the part about doing things the old way but ive spent a fortune and the best part of 3 years of my life fixing the wrongs of the previous owners and I'm not really sure if I can be bothered to lathe and plaster it! Plus things are progressing fast here in my part of the world, the brave new world is getting nearer and nearer so to speak, and I will likely be selling up shortly, sadly. I'll probably just do this part quickly and cheaply for once. xD

Edited by spunko
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2 hours ago, spunko said:

There was some woodworm when I moved in but had it treated and every spring there are less of them. I'm hoping now that I've exposed more timbers they will dry out more.

There's also a huge old chimney stack, just to the left of the photo in the middle of my house, I'm told it has original brickwork and masonry eg wattle and daub ,vwhich supports the entire house timbers. that's why there's no cross beam here in this room but the larger rooms have proper bressumer (?) beams.  in fact to the left of the first photo you can see the old one that is holding up my bedroom. The construction of this house I'm constantly being told by tradesman is different to anything anyone has ever seen, generally meant in a bad way I suspect. xD

PS My house is as old as yours @Conniption but my reasoning is the timbers have been there for 500 years so I would be very unlucky if they did collapse now.

totally on board with everything you just related, sounds like both our houses were built some 400+ years before planning permission and by people who had just enough knowledge to stack one stone atop another and you're right, we could have spent a fortune getting everything just so but in my case had to call it quits before it hoovered up every penny we ever earned. Both have held up this many centuries, what are the odds they will cave in during our stewardship? Minimal-to-none, I expect.

Our doughty little ships sailing the seas of time.

Like anything worth having, after a certain point, it's a leap of faith.

 

Edited by Conniption
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22 minutes ago, spunko said:

@Caravan Monster

The cross beams are i was told by someone supposedly knowledgeable on these things that they're supporting the roof. Here's a photo, they are nailed into the timbers going diagonally up.

Varied dimensions but about 6cm on average each side. they go E to W whereas on the other floors the thicker beams go N to S, which is strange. 

Worth adding I have a very shallow width house, it's almost like a ship from the side, and I wonder if this explains the roof setup.

16024263061413924328225952084531.jpg

By the sounds of it they are similar dimensions to floor joists. I would guess the bigger beams you can see are supporting floor joists in the middle of their span. The big beams are doing the same job that steel beams do in modern houses.

I would be wary of using those timbers alone to support a floor, even for occasional walking / crawling on, not strong enough from what I can see.

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5 hours ago, spunko said:

My bedroom has old timber beams in the ceiling but for some reason they were covered up by horrible old chipboard that was rotten due to a water leak and mouse piss. :CryBaby:

I decided to expose the beams and put plasterboard above them, screw the plasterboard on to the beams, and then get new Celotex type insulation above that (previously it was that horrible fibreglass stuff that mice love). 

The only problem is whenever I need to go into the attic I've been using crawl boards balanced on the old beams. But now the Celotex and plasterboard will be what I'm leaning the crawlboards on... 

Will this lead to loads of movement? the timber beams are old and have a bit of give in them. I was going to just use gyprock and scrim below to seal the plasterboard joints but now I'm worried that the amount of movement from above will cause the joins to break... any one got any ideas? 

PS plasterboard not fixed in yet.

 

From below

IMG_20201011_113109.jpg

From above in attic

 

IMG_20201011_113126.jpg

You've not totally funked it up.

You should run 3x2s at right angles to the beams, on the top side, centered at 600mm. With the PB to the underside of them. The Kingsland then drops in the gap, then board over.

Personally I'd have put OSB over the lot first, filled the gaps bellow with PB, then 3x2 over the OSB.

 

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as above I was thinking OSB (instead of plasterboard).....Froggies use it a lot, in fact I saw a decent size open plan house with it and a fab homemade metal staircase......was expecting it to look sh!te but it looked really good!

Whilst I'm here, my roof is fooked and sagging....something has eaten the circa 70 year old oak beams....some have sagged but they don't look like they're about to collapse

I did think about trying to put a couple of RSJs in but they'd need to be about 9 meters long so not a quick DIY job...

I should probably treat the oak but that stuff ain't cheap and the bugs look like they've 'buggered off' somewhere else....hopefully not still in the cellar but they've been in there at some stage too, arrrgghhh

Thoughts? cheers

Edited by 5min OCD speculator
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3 hours ago, GBDamo said:

You've not totally funked it up.

You should run 3x2s at right angles to the beams, on the top side, centered at 600mm. With the PB to the underside of them. The Kingsland then drops in the gap, then board over.

Personally I'd have put OSB over the lot first, filled the gaps bellow with PB, then 3x2 over the OSB.

 

If I'm understanding correctly, you mean for added strength? Or to basically create a slot for each Kingspan insulation block to fit into?

If that's what you mean sadly that won't work because the existing timber beams aren't machine cut, and aren't straight at all.. They're basically all over the place. So I'd need to cut each Kingspan to size.

I'm thinking now anyway to ditch the Celotex/Kingspan idea, and just get new rockwool, it's dirt cheap and I won't be using my attic for anything (not even storage) so it's purely for insulation purposes. Plus it will weigh less than Celotex. Hulking around bits of Celotex up through the tiny hatch isn't going to be fun. 

So to summarise I am planning to: lay the plasterboard and screw it to the timber beams. Then for the insulation I'll use loads of adhesive spray to stick the rockwool to the top side of the plasterboard so that hopefully mice won't get underneath it and keep me awake.

 

 

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13 minutes ago, spunko said:

If I'm understanding correctly, you mean for added strength? Or to basically create a slot for each Kingspan insulation block to fit into?

If that's what you mean sadly that won't work because the existing timber beams aren't machine cut, and aren't straight at all.. They're basically all over the place. So I'd need to cut each Kingspan to size.

I'm thinking now anyway to ditch the Celotex/Kingspan idea, and just get new rockwool, it's dirt cheap and I won't be using my attic for anything (not even storage) so it's purely for insulation purposes. Plus it will weigh less than Celotex. Hulking around bits of Celotex up through the tiny hatch isn't going to be fun. 

So to summarise I am planning to: lay the plasterboard and screw it to the timber beams. Then for the insulation I'll use loads of adhesive spray to stick the rockwool to the top side of the plasterboard so that hopefully mice won't get underneath it and keep me awake.

 

 

Just give up with the modern stuff and use mud, horse-shit and willow twigs from your back garden, the horsey wimmin and your local twiggeries.

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23 minutes ago, 5min OCD speculator said:

had a close up look at your wood, christ it does look fucked.....I'll have to get some pics of mine to give you a laugh

Bit of advice. A while ago, a picture of my arse did not go down very well on here at all.

I see no reason why your nob pictures should fare any better...

 

XYY

Edited by The XYY Man
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8 hours ago, spunko said:

@Caravan Monster

The cross beams are i was told by someone supposedly knowledgeable on these things that they're supporting the roof. Here's a photo, they are nailed into the timbers going diagonally up.

Varied dimensions but about 6cm on average each side. they go E to W whereas on the other floors the thicker beams go N to S, which is strange. 

Worth adding I have a very shallow width house, it's almost like a ship from the side, and I wonder if this explains the roof setup.

16024263061413924328225952084531.jpg

 

I haven't really explained it very well. These beams are the A part that you referred to, @Conniption. My house has sunk so they've raised the internal floors up. Think of it like this, and it'll be easier to understand: the first floor is effectively a half first floor and half attic. The attic space has been reduced so as to fit into the first floor, as the house has sunk so much (and people were of course smaller too). 

 

@Caravan Monster I agree with the part about doing things the old way but ive spent a fortune and the best part of 3 years of my life fixing the wrongs of the previous owners and I'm not really sure if I can be bothered to lathe and plaster it! Plus things are progressing fast here in my part of the world, the brave new world is getting nearer and nearer so to speak, and I will likely be selling up shortly, sadly. I'll probably just do this part quickly and cheaply for once. xD

Same as my old roof.  An old barn where they squeezed in an upper floor.  But I also have a large purlin running either side supported by the gable ends and a massive oak "A" frame in the centre.  Presumably helps spread the load and stop the (relative to today's) thin rafters from sagging.  Presumably the end of your rafters are birdmouth cut into a wooden wall plate on top of the wall either side of the roof.  That helps too.

Same nails which look a bit dickie so may add some more cross members/beams and screws.  No way I would want to crawl over them, although amazing what spreading the weight can support.

I used celotex (i.e PIR board) between and above the beams once in a small newer bit and will rip it out and replace with rockwool as it is above a bathroom and I don't want to trap moisture.

I cleared up some unused rolls of rockwool from a field a few weeks back.  Been there for years.  No sign of mice at all!

I quite like mixing old and new where the old can highlight the new.  I use traditional methods, especially where say I was infilling between two beams.  But overboarding the beams, I would be tempted with plasterboard with the joints over the beams.  It highlights the beams.  Depends on taste.  Never plasterboard a wall though as I like a semi coarse texture (e.g. mid hemp plaster).

Sounds like we're all trying to fix past bodges.  Cement is the worst.  Just rebuilt a wall with a hydraulic lime mix.  Just add water and paddle mix small batches.  Lovely stuff.  Much nicer than sand and cement, and tough.

Just a mention on cluster flies.  I'll be netting along the inside of my rafters before I put the ceiling back to keep them out.  Mind you, my Red Tops have been awesome this year.  The netting also restrains the rockwool, maintaining the air gap between the rafters. 

For some reason I found loads of cheap rockwool warmer than PIR board.  Plus rockwool is nice and fire safe!  And it may be itchy and bad to breath but cutting PIR board without a mask ain't good for you either!  One thing I defo went against after research was sheeps wool.

PS:  I had woodworm too.  Par for the course and not necessarily an issue.  I had it professionally treated for the cert but put a bit more down as I go.  And old oak is as tough as steel.  Try cutting it!

Edited by Harley
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Another thought - have you considered air flow while you have access?  These roofs are not known for soffit vents and the like as they originally had good airflow between the slates/tiles as there was no bitumen sarking back then.  That often got added on a re-roof but no-one thought about ventilation at that time.  May be worth looking at any required improvements.  For example those plastic vents you can put between the overlapping bitumen above the rafters to open a gap are a quick fix.  Or full blown vents.

Edited by Harley
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Mice.  I keep finding mummified remains.  Not much to do except a hatch to place traps, smoke bombs, etc and maybe install an electricity supply while you can to plug in a deterrent, if you feel they work (for squirrels too!).

Edited by Harley
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IMG_20201011_113109.jpg

My beams look a bit similar.  In my case I decided they weren't good looking enough for display purposes so will plasterboard under as it originally was.   

Sometimes I lay proper nice aged oak thin "fake" beams below the plasterboard if all that plasterboard looks too out of place!

I'll also lay rockwool on netting first before plasterboarding to make things easier (no crawling around, do it all from below).

Edited by Harley
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9 hours ago, Harley said:

IMG_20201011_113109.jpg

My beams look a bit similar.  In my case I decided they weren't good looking enough for display purposes so will plasterboard under as it originally was.   

Sometimes I lay proper nice aged oak thin "fake" beams below the plasterboard if all that plasterboard looks too out of place!

I'll also lay rockwool on netting first before plasterboarding to make things easier (no crawling around, do it all from below).

I'm umming and arring between leaving them, and painting them. I don't like painted beams much but most people paint theirs because they're coated in that black tar shite that is a bastard to remove. I quite like whitewashed beams but I think in a few years time whitewashed wood is going to be "very 2020" as it's bloody everywhere.

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9 hours ago, Harley said:

Mice.  I keep finding mummified remains.  Not much to do except a hatch to place traps, smoke bombs, etc and maybe install an electricity supply while you can to plug in a deterrent, if you feel they work (for squirrels too!).

I've never had much luck with those noise emitting things and if you live in an old house prevention is better. If you seal one hole up in the attic they will find another.  It's better to prevent them getting that high in the first place. Every so often I camp out in my garden for 2 hours or so at dusk and sit and wait. Watch where they are going in and then fill it. It's boring but I'm slowly winning the war.

This autumn I've only had 2 mice so far, whereas last year I must have had 10 by now. Fucking bastards.

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