and we have now had more time to think about making it watertight following the suggestions here.
The vague plan is to try not to fall off while we remove the exterior strips beside the curved uprights, then apply liberal sealant before re-fitting them. This should make a good start at sealing the places where the t&g panels butt up to the decorative bits. There are also some drips through some tiny cracks in individual t&g slats, so....
Then apply some sort of paint.
My son has asked and been advised to use linseed oil based paint, but the price seems utterly horrendous. I've used Jotun 2-part epoxy primer plus a reddish-orange top coat on the boat to paint over decaying clear epoxy + varnish surfaces and it is wearing really well, forming a robust skin over the plywood. I know nothing about the relative disadvantages of either paint, except that the linseed should allow movement and some leakage perhaps, whereas the epoxy might or might not crack.
Can anyone advise on these or other paint solutions. We also need to redo the standard shed paint on the walls, so we don't want the roof to look too out of place.
I think there may be some overkill going on here. Surely, just suitable coloured mastic down the grooves, followed by ordinary fence preservative of your preferred colour will do the job?
The reason I want to go for overkill is that this summerhouse is really ideal for his mum, SWMBO, to go and relax in in the afternoons. (We are not that young!). It has mains lighting, plus a distribution box for the feed to the fish pond pump, filter system and fountain, so there is a fair amount of electrical stuff about. I will be asking about the fountain later.
When we have been in there and it has started to rain, there are substantial drips from the light, over the light switch and beside the dis unit. Apart from these there are also drips from the small cracks, some of which are over the recliner chairs..
There is evidence of earlier mastic. It now looks like a piece of plastic tube just draped like a bit of old rope loose on the roof. We want to do a better job because we have to try to get each thing that needs doing put right so that we don't have to come back to it. Everything is in a bit of a state, but recoverable I think.
We have the ride on mower going now and the lawn is starting to look great. The Billy Goat vacuum is next before the trees really start to shed. So much to do, so little time.....
Have you posted any pictures of the actual problem bits Bill? Wood is always going to expand and contract, and in my experience, any joins you try to paint over are going to buckle up or split one way or another. that's why for sealing one generally uses mastic as it doesn't really set. It would only really come adrift on its own if the wood was rotten. Was your tongue and groove originally felted over perhaps?
No, we can't easily get pictures, but the roof is identical to the one in the url posted. It is obviously designed to be decorative rather than watertight, and the publicity material for the new version shows it with no felt. It does look nice and there are 2 generations of SWMBO's to be pacified.
The mainly triangular roofing t&g panels seem to be pre-assembled using staples up from underneath. Presumably originally the walls were put up on site, then the (approx) 6" or 8" x 1" scalloped (is that the word?) decorative roof frames put into place. Then the t&g panels just dropped in and 1"x1" pieces nailed into place beside the framing to hold them down.
It doesn't look as if there is any rot - I think the whole thing is made of pre-treated timber - but there are places where you can see daylight through a tiny crack or where panels don't quite fit tightly. There are also one or two pieces of t&g which are darker than their neighbours where I suspect the dampness has had an effect.
The silicone mastic sort of stuff seems to have been pulled out in one long piece, so maybe it didn't grip the treated timber properly and maybe animals had a fun time pulling at it. That's why we think putting mastic under the 1" capping pieces would be a good idea.
I don't know where he got the idea that linseed oil paint would allow movement and still seal, but I think the price was over £30 for 750ml. I was thinking that the epoxy paint would either grip and hold over large areas or effectively form another roof on top. On the boat it's mainly on ply, so it's fine there. There are some tiny cracks in the t&g and I've marked the ones that the drips come through.
I think I'm happy with the mastic where it can be held in place, but what I really need is advice on the best paint. I hate the useless water based shed paint. It doesn't work well on my shed and fence or other local fences (I'm now totally oil-based for fences) and it is falling off this summerhouse where it has been used. I find buying paint utterly depressing as it rarely seems to say what it is or does on the tin. Like a BT brochure it's just loads of waffle and not a fact in sight.
The site is high and faces south, so we have to be ready for extremes of weather.
There seems to be a plethora of misunderstandings here and I will try to help.
First never seal timbers and expect them to last. Any form of resin will last x years (3-5) and then cause more rot than it fixes. What is more if there is any condensation from under it there is no escape. So how to fix? First make the wood water repellent (water repellent preservative stains) not water proof. Saddolins etc are good but do them every year or at most 18 months =3D takes only minutes with a spray and no need to remove old WRPS. concentrate on ensuring any correction is done in a ventilated fashion. Sealants are not likely to help with this. So I would be looking at flashings of say lead in risk areas. I would concentrate on getting my water protections underneath the structure with battens and vapour porus roofing felt. (stuff the looks you want to be dry!)
Where you do need to protect vertical joints, add a batten suitably shaped
I wouldn't waste the money on trying to seal it all up using mastic or any other sealer. You probably won't catch all the leaking parts. The timber will expand and contract due to weather changes and if only one or two pinprick holes appear, the water will travel along and down and along etc and you'll spend the rest of your life trying to keep it sealed.
If you need to have it watertight then you'll need to form a waterproof membrane below the roofing slats (in this case the framing as well). Either take the roof off - fit a dummy roof underneath, felt it and replace the original roof. Or felt the internal surface of the existing roof - use straps to keep it tight to the roofing slats and framing. Leave enough felt hanging down the inside walls at the eaves so that you can lift roof sections of the original roofing from outside and push the felt flap out over the wallboard then fit the roof edges down again. I'd place dollops of roofing mastic (penny size) between the felt and exterior roof timbers where the screws will run through into the wall boards. This way the water will still get through the cracks/spaces but be shed down to the eaves and out over the wall boards just like a normal felted roof. You could even fit a guttering to capture the water and run it away down a downpipe to keep it off the walls. Totally invisible from outside, you keep the look of the original structure.
If you don't like the look of the felt on the inside of the roof, you could clad it using t&g fitted onto the straps you will have there, keeping the felt up against the original roofing.
I tried to look at the link you gave earlier, but, apart from my Outlook Express chopping it in half, it comes up as no longer valid on the website. But it was really the state of the wood I wanted to see, though the design might have helped.
I don't think you should be using silicon that sets on a wooden roof in the sun. Like your boat, as it warps and changes with the weather it needs caulking with something that can change shape and still stay stuck. It would take a long time for mastic to get to the state your silicone was in. So, yes, you would be best with oil based mastic and oil based paint or wood treatment. The boards that really do have tiny cracks in could just be sealed by teasing in pva with a palette knife/wall paper scraper etc. (wiping it off the surface wood before it dries though.) If you feel some of your gaps need more than mastic you could beef it up with hemp fibre as you would caulking a boat.
Advice on the best paint is always a pain. I went though a lot of agonising over what to use on a picket fence I made. Ended up using 5 star wood treatment and a special 'breathable' paint that would move with the wood. That wonder stuff didn't actually stick at all, but all the dirt did stick and it was a filthy mess a year later. Next time I just used ordinary exterior white gloss and it has been fine. Had I read the 'diy wiki' on paint before hand I would have used 'lime putty' from the off: but then I wasn't looking for waterproof between the palings.
Similarly, I've now had three or four goes at getting black gloss to stay on a window sill that I cut back, but was stupid enough not to cut right back out of sight, but stop at the good wood. Even though I matched the wood with similar stuff from an old door frame, no paint whatever will remain intact across the join, there is always enough differential expansion to crack it.
Your summer house roof is going to get very hot, so I doubt that an epoxy paint that goes hard will stay on. Yacht varnish is often touted for outdoor furniture: but what goes into it nowadays, I don't know, as I now just use solvent based 'creosote substitute' probably as you do. Still, once your holes and cracks are filled, it probably just needs you to go over it with something oily every year or two. Even linseed oil dries to a varnish eventually (though the stuff I painted on my walking stick last summer hasn't actually dried yet!).
Incidentally, you say t&g, but might it be shiplap? That is more usual on outdoor stuff and gives a longer overlap than t&g, but if the overlapping part splits then the water will get through, but again, you may be able to stick it back with outdoor pva. Anyhow, keeping water out isn't exactly rocket science, so I'm sure you will see what is needed once you get going.
There seems to be a plethora of misunderstandings here and I will try to help.
First never seal timbers and expect them to last. Any form of resin will last x years (3-5) and then cause more rot than it fixes. What is more if there is any condensation from under it there is no escape. So how to fix? First make the wood water repellent (water repellent preservative stains) not water proof. Saddolins etc are good but do them every year or at most 18 months = takes only minutes with a spray and no need to remove old WRPS. concentrate on ensuring any correction is done in a ventilated fashion. Sealants are not likely to help with this. So I would be looking at flashings of say lead in risk areas. I would concentrate on getting my water protections underneath the structure with battens and vapour porus roofing felt. (stuff the looks you want to be dry!)
Where you do need to protect vertical joints, add a batten suitably shaped
Chris
Nicely put, I was trying to waffle my way there, but you put it in a nutshell.
Thanks to everyone for the thought provoking advice. I have discussed briefly with son and we both now feel very tired.
I've put some photos up at
formatting link
me the roof panels do look like t&g, but with a couple of the bottom pieces being different, so they may be shiplap. We don't necessarily need total watertightness, just a good enough job to stop water dripping from the light and switches
The real problem with felt would be our abilities, the complexity of the roof and the looks. I don't think the ladies will accept stuffing the looks. If the weather keeps on like today, it will be next year for the job anyway.
It's shiplap: the boards can be seen to be butting up on the inside but overlapping on the outside. Not ideal for a sloping roof unless v steep because the overlap is not all that great and the scalloped top edge makes the join even less so. That said, I'd say your Summerhouse looks to be in much better condition than I had imagined, and your main problem I would say is the horrible red wood treatment! I should think that once you have plugged any obvious knot holes and cracks, your main job - or someone helpful's is going to be to get up there carefully for a few days and go over it with a wire brush to get as much of that red mess off as poss before spraying the whole thing inside and out with a nice water resistant wood preservative treatment, that will soak well in. (Shame you missed the chance in this years unusually long dry spell.) As the wood inside is a nice oaky colour I'd start with something light. There do not seem to be any drips of red down the inside of the boards, so I would say that was not very heavily applied in the first place.
Once you've got it so that it isn't going to absorb water, then you just have a few minor leaks to deal with I'd say: you could even just cut some nice shaped pieces of felt to stick over where the actual light is, but it looks like it is probably a sealed unit and reasonably safe, but do take it down and check any grommets and seals are still working. Then make sure any wiring flex has loops in strategic places so any water that does get on them drips off rather than running down into any switches etc (I would imagine it may already be arranged like that.)
You will find, as the wood is - or was till recently - very dry, it will soak up gallons and gallons of creosote substitute (I just use Travis's own brand: seems fine to me), so we are probably looking at spraying it on with one of those pump up garden sprayers (wearing proper mask and getting out frequently while doing the inside). My little shed ~7'x4' (with felt roof), took about 4 gallons after it's initial restoration - floor included). Ideally I would empty it out and do another gallon inside and out every year - as it looks so much nicer when the treatment is fresh.
Just get yours a different colour ASAP is what I say!
What sort of wood treatment are we talking about here? Water-based with wax inside or oil-based? I've never had much success on shed or fence with water based products. All the things called creosote substitute seem to turn out a very dark colour no matter what it says on the container. I've been using white spirit based things in light colour or clear on the sheds and fences here and they seem to soak in, work and look fine. Is this sort of thing water resistant in the way you are advocating?
It's the gaps where the roof panels connect to the roof framework that is the main source of the water, we think. So we still think taking the external capping pieces off and putting some sort of flexible non-setting gunge underneath would be worth doing. Again, is there a name for the best sort of gunge?
Yes, I was thinking of making a drip cover for the light, and maybe a small hat over the light switch .
Yes. As Chris said: it's water repellent you want, so water based would not be favourite. My local Travis Perkins does 2 colours of 'creosote substitute' and one is quite a bit paler than the other, you will probably find even paler if you look around, and any colour you like if you go for ranges like Sadolins - though I generally favour the darker in truth. Once you have got the wood to absorb as much of such a basic treatment as poss: then you could look at the Sadolins for the final colour on the outside perhaps.
I did wonder about something like the 'waxoyl' they used to spray inside car doors and the like, but I would imagine that just like candles left in the glove compartment, they would end up on your carpet after a sunny day. (Though in some respects such an annual melting and hence pore filling might not be such a bad idea!)
If you are going to do that you can probably cut some rubber sheet to go along under the battens - or roofing felt - and the gunge is mastic.
Better to put the cover on the outside if you can: even if drips can't get into the electrics it still does not look good having water dripping off them. It should be fairly doable to prevent any leaks in the small area above the light, even if you can't get the whole roof 100% drip free.
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