Problems with T&G Ceiling

[michaelR]

I don't know if anyone has any ideas but I'm having big troubles with my TulipWood T & G ceiling. Its 'popped' away from the battens recently and there was a slight sign of damp in the wood so I removed and resealed the mushroom vents - as its the only place it could have come from - and had damaged parts replaced with new Tulipwood by a carpenter - cost around £500. This only happened in one area of the boat.

 

Now a couple of months later its happened again in exactly the same place -slightly off centre and not directly under the vents but its happened along the same line in the bedroom as well as the lounge/galley like before. There is absolutely no sign of water coming in at all, but obviously the weather has got colder and damper?

 

Don't want to get it fixed before I find out why its happening.

 

Thanks

 

Michael

 

[Alan de Enfield]

Just a wild guess but differential expansion ?

 

Was it fitted in the 'warm' and now its colder the steel is contracting 'pulling' on the battens and loosening the T&G ?

Condensation in the roof ?

[The Bagdad Boatman (waits)]

Condensation will swell the wood and make it pop off the battens. Wood is not vapor proof so any cooking, shower or breathing will produce vapor which condenses on cold steel and drips. Insulation wadding is poor. Kingspan foam with foil each side is good, there is a wadding with foil each side which is also good.

[Ex- Member]

Its 'popped' away from the battens

 

 

Did you check weather the batten had also removed it's self as well.

 

We have T&G pine @15mm thick so expected there's going to be a lot of movement, that's why we screwed and plugged every twice every18 inches. we've never suffered any noticeable movement or damp. Our battens were also TEK screwed to steel ribbing as well as glued. If any batten departs from the steel it's likely to condensate on any bear steel and then over time exacerbates the problem as more and more moisture is absorbed.

 

I've never worked with Tulipwood so don't know it's characteristics, sounds lovely though. We have cherrywood on the floor fixed in a similar manner, not T&G though but that expands & contracts quite considerably with no moisture apparent and it's 1 inch thick too.

Edited January 4, 2014 by Julynian

[Grace and Favour]

OP - My first thought would be condensation - so how well is your boat top insulated, please?

[Mike Jordan]

As suggested above the most likely cause is the expansion of the boards caused by the increase in atmospheric moisture. The power of expanding timber is enormous and can cause floor boarding to lift up and joinery joints to fail. If you look in my photo gallery you can see examples of solid timber door panels which have expanded and destroyed the doors during their first winter, this from a so called quality boat builder. The best solution is to leave a gap between the boards to allow the boards to expand as they take up moisture.

[the grinch]

when I fitted out mine I used damp T&G and screwed the battens to the steelwork then screwed each timber with 1 screw centrally in each plank the wood expands and retracts happily and never had any issues over 20 years the voids above the T&G are stuffed full of rockwool I suspect that you may not have sufficient insulation

[David Schweizer]

If the boards have been fixed by secret nails, a popular (and in my view misguided) proceedure, I would support Julynian's approach and suggest that they should be screwed to the battens. I would also recommend that if they are being affected by differetial of temperature/ambient humitity, that the back of the boards be given a couple of coats of good quality varnish before fixing, that should protect them and help prevent warping.

[Ex- Member]

If the boards have been fixed by secret nails, a popular (and in my view misguided) proceedure, I would support Julynian's approach and suggest that they should be screwed to the battens. I would also recommend that if they are being affected by differetial of temperature/ambient humitity, that the back of the boards be given a couple of coats of good quality varnish before fixing, that should protect them and help prevent warping.

 

Blimey, there's not one single nail anywhere in our boat, I would be flabbergasted at such a thought.

 

Absolutely, asking for trouble.

 

I'm sure a proper carpenter wouldn't have fitted with nails though. Possibly grip nails, I never fancied using them though. Much prefer a good screw

 

I note also Hamsterfam mentions Rockwool. This is an excellent solution for a T&G roof. You can apply as you go and ensure that the cavity is fully filled and tight to the steel.

 

Could also save on Spray foaming costs, even if you found a company that gives you the 50mm you're paying for

 

You can now get Cellotex at 12mm thick combined with 40mm rockwool would ensure a tight fit of Rockwool to a 50mm cavity steel roof and also slip in cut sheets of 12mm Celotex as a vapour barrier.

[David Schweizer]

 

Blimey, there's not one single nail anywhere in our boat, I would be flabbergasted at such a thought.

 

Absolutely, asking for trouble. <snip

 

 

Likewise, I must have used literally thousands of brass screws on our boat.

Edited January 4, 2014 by David Schweizer

[Ex- Member]

 

Likewise, I must have used literally thousands of brass screws on our boat.

 

Yeah

 

Screwfix loved us. I think it was 1700 in the ceiling alone, and every one plugged with 8mm plugs we cut using a pillar drill

 

A couple of weeks later I discovered these http://www.diy.com/diy/jsp/bq/nav.jsp?action=detail&fh_secondid=9275450

 

Although the plugged effect does look good, well to me anyway

[David Schweizer]

 

Yeah

 

Screwfix loved us. I think it was 1700 in the ceiling alone, and every one plugged with 8mm plugs we cut using a pillar drill

 

A couple of weeks later I discovered these http://www.diy.com/diy/jsp/bq/nav.jsp?action=detail&fh_secondid=9275450

 

Although the plugged effect does look good, well to me anyway

 

Those clips still have to be nailed as there is insufficient clearance for screws, and they will not prevent the boards from moving under stress. As for plugs, I did not use any. Ss long as they are all in line and evenly spaced, I am, quite happy for the screw heads to be visible.

[Ex- Member]

 

Those clips still have to be nailed as there is insufficient clearance for screws, and they will not prevent the boards from moving under stress. As for plugs, I did not use any. Ss long as they are all in line and evenly spaced, I am, quite happy for the screw heads to be visible.

 

Clips are screwed not nailed, I would have thought one inch thick of batten would suffice.

 

As for plugs, I did not use any. Ss long as they are all in line and evenly spaced, I am, quite happy for the screw heads to be visible.

 

 

If you like screw heads then Cool!

[Chalky]

 

A couple of weeks later I discovered these http://www.diy.com/diy/jsp/bq/nav.jsp?action=detail&fh_secondid=9275450

 

Although the plugged effect does look good, well to me anyway

 

Used those to to our T&G roof. Work very well and allow the planks to move but don't split or warp. A lot easier than screwing and plugging.

[Ex- Member]

 

Used those to to our T&G roof. Work very well and allow the planks to move but don't split or warp. A lot easier than screwing and plugging.

 

I did suffer some p1ss taking with regard to these clips The foreman at the particular boatyard we were at came on to the boat when it was finished, so there I am showing off my handy work, no screws only 14 butt joints in the first 35f/t of ceiling etc etc when he piped up and said F__K me haven't you heard of these, and held out a T&G clip

 

He had been fitting out a boat with T&G and heard about how I did it

 

He also offered to crane in our compost loo when it arrived

[David Schweizer]

 

Clips are screwed not nailed, I would have thought one inch thick of batten would suffice.

 

 

If you like screw heads then Cool!

 

I do, I think they create a more traditional appearance.

[Ex- Member]

 

I do, I think they create a more traditional appearance.

 

Nowt wrong with tradition!

[Keeping Up]

Our boat builder always fashioned his own t&g saying that the pre-formed boards never allowed for enough expansion and movement in a boat. They have wider tongues and deeper grooves, and also a shaped pattern which disguises the fact that they have been fitted with plenty of clearance. They still look good after 21 years even though they are just woodstained pine.

[David Schweizer]

Our boat builder always fashioned his own t&g saying that the pre-formed boards never allowed for enough expansion and movement in a boat. They have wider tongues and deeper grooves, and also a shaped pattern which disguises the fact that they have been fitted with plenty of clearance. They still look good after 21 years even though they are just woodstained pine.

 

It's called a "side bead" Alan, and is a very old method of disguising shrinkage, used by joiners for centuries. I also agree that the tongue and grove joint applied to most commercially manufactured boards is too shallow, and tends to be applied universally irrespective of the width of the board, wheras it should deepen in proportion to the width of the board.

[michaelR]

Thanks for all the replies and advice, a couple of things; The boat is less than 12 months old and was completely spray-foamed internally after being battened and its had no-one living on it so I'm thinking it shouldn't be condensation?

 

The batons are fixed to the steel structure of the boat by Screwfix self-drilling screws and the batons haven't come loose..

 

Surely the wood should shrink in Winter not expand?

 

I'm thinking that I'm gonna have to take down all the ceiling and start again so I might look up how those T&G clip things actually work.

 

I don't want to start on the bloody thing until I'm certain that it wont happen again.

[Mike Jordan]

Wood inside some centrally heated houses can tend to shrink in the winter but any in an unheated area will take in moisture and expand in the winter months. The doors shown in my photo were just two out of a total of twenty nine doors, all of which had been destroyed over the first winter in the damp atmosphere of the marina. When the owner returned in the spring the inside of the nice new boat looked like a war zone. If you refit the boards in the winter they should be OK but will show shrinkage gaps in the heat of the summer, not a problem providing the shrinkage is not greater than the width of the tongues.

[Ex- Member]

Wood inside some centrally heated houses can tend to shrink in the winter but any in an unheated area will take in moisture and expand in the winter months. The doors shown in my photo were just two out of a total of twenty nine doors, all of which had been destroyed over the first winter in the damp atmosphere of the marina. When the owner returned in the spring the inside of the nice new boat looked like a war zone. If you refit the boards in the winter they should be OK but will show shrinkage gaps in the heat of the summer, not a problem providing the shrinkage is not greater than the width of the tongues.

 

A wee tip if using pine and intending on staining it up. So those shrinkage gasps don't look awful and streaks of unstained wood is visible in said gaps. Stain the tongues roughly to match your finish before fitting.

[David Schweizer]

Thanks for all the replies and advice, a couple of things; The boat is less than 12 months old and was completely spray-foamed internally after being battened and its had no-one living on it so I'm thinking it shouldn't be condensation?

 

The batons are fixed to the steel structure of the boat by Screwfix self-drilling screws and the batons haven't come loose..

 

Surely the wood should shrink in Winter not expand?

 

I'm thinking that I'm gonna have to take down all the ceiling and start again so I might look up how those T&G clip things actually work.

 

I don't want to start on the bloody thing until I'm certain that it wont happen again.

 

You have just identified the conundrum with wood. All timbers will shrink or expand according to the ambient moisture in the atmosphere, softwoods more so than hardwoods, although over time (I mean decades) the differential will reduce as the timber naturally seasons.

 

Basicly in an unattended boat, the tinber cladding will expand significantly during the winter, even on the best isulated boat, wheras similar timber may shrink in a centrally heated house because the atmosphere is being artificially dried. whether this applies to a boat permanently heated during tghe winter i do not know, but I suspect the heating will probably just about compensate for the increased moisture in the atmosophere around the boat.

 

Because of the inevitable expansion which occurs during the winter, cladding fitted during the summer should incorporate an expansion gap between the boards to accomodate that expansion, The size of the gap will vary according to the timber being used, but I would allow one thickness of a cornflakes box for hardwood, and two thicknesses for soft woods.

 

As already mentioned the shrinkage and expansion will, over time reduce, leaving the boards noticeably narrower during than when installed, even in the dampest winter. Some of the boards on our boat which were close fitted during a winter, now have gaps of up to 2mm in the winter and a bit more during the summer, One day i may startv the process of closing up the gaps, but that job will have to wait until the re-fit has been finished.

 

Another fixing point to observe is to only fix the boards along one edge in order that natural expansion/contraction can take place, other wise you could end up whith board splitting during the summer, also when fitting furniture to timber bulkheads, it is a good idea to make oblong holes in the furniture panel for the screws, so that they can move independantly from the bulkhead particularly if the timber grains run at right angles. ( an old cabinet maker's trick, often signalled by loud bangs from the backs of oold cabinets when the timber moves)

 

As far as the cladding clips are concerned, my only concern is that once fitted, it can be a pain to remove a few boards if you need to gain access behind them to make alterations to wiring etc, as you will have to remove them in sequence, wheras with direct screws you can release a couple of board either side of the one you need to remove and use the expansion gaps rto sliede the boards up or down. As have had to remove boards from virtually every panel of wall cladding on our boat at some time or other to upgrade the wiring, I would have found clips very inconvenient.

Edited January 5, 2014 by David Schweizer

[Chalky]

Another tip is to wax the boards, not varnish them. On the first roof I fitted in the boat I invisibly nailed it then varnished it. Looked great however 6 months later there were splits every where, helped by the varnish which had glued it all together! The second roof (expensive lesson) was fitted with the clips described earlier. I arranged it so all the planks ended at the same distance then butted up the next set. The join was covered by a piece of beading held in place by clear silicon sealant. This allows movement and means that I can get it down for maintenance if required.

[Ex- Member]

Another tip is to wax the boards, not varnish them. On the first roof I fitted in the boat I invisibly nailed it then varnished it. Looked great however 6 months later there were splits every where, helped by the varnish which had glued it all together! The second roof (expensive lesson) was fitted with the clips described earlier. I arranged it so all the planks ended at the same distance then butted up the next set. The join was covered by a piece of beading held in place by clear silicon sealant. This allows movement and means that I can get it down for maintenance if required.

 

Our ceiling is varnished, the trick is not to let varnish flow in excess into the T&G when you apply by brush and if you do then ensure you brush it out.

 

What you describe hasn't happened anywhere on ours and it's had 2 coats of varnish. It's also worth waiting for some shrinkage to occur before varnishing, we stained first but didn't varnish until mid summer.