|
| Author |
Message |
niceboy
Member
|
# Posted: 20 Mar 2012 09:29pm - Edited by: niceboy
Reply
Nearly finished the basic structure of a small cabin on my roof. Have used tongue and goove planks, screwed to the frame. After the first downpour, there is some moisture running down between some beams and the planks. Is it permeating in along the screws? Can I stop this?
|
|
dvgchef
Member
|
# Posted: 20 Mar 2012 10:16pm
Reply
niceboy
Granted, I'm tired, but I'm not sure what you mean.
Where are the T&G planks? On the roof? Do you have any tar paper on the roof?
|
|
MtnDon
Member
|
# Posted: 20 Mar 2012 11:38pm
Reply
If the T&G is screwed to the rafters, the T&G joint itself will not be tight enough to prevent water incursion. They make a solid roof and look great from the underside. However, you need a weather resistant barrier like roofing felt with a finish roof like shingles or metal panels to complete the waterproofing.
If you have all that and have serious amount of water coming through there is some problem. It doesn't sound like it in this case, but it is possible for enough condensation to form on nails or screws that penetrate the roofing into the interior space, that water forms around the fasteners and looks like a leak.
|
|
niceboy
Member
|
# Posted: 21 Mar 2012 03:38am
Reply
Wow, thanks for quick responses - my first post on any forum.
The planks are on the walls. The roof (covered with roofing felt) is fine.
Its only a small amount of water, just showing as dampness on the outside of the vertical beams.
I suppose I'm just wondering if it's possible for water to enter where the screws are, or should I be looking somewhere else?
|
|
Martian
Member
|
# Posted: 21 Mar 2012 09:09am
Reply
A wind-driven rain can be forced through the T&G joints just as a long rain may wick through at the screws. Water is very good at finding places to enter a structure.
Tom
|
|
sparky1
Member
|
# Posted: 21 Mar 2012 10:32am
Reply
just wondering if (Thompson's Water seal) Might work---water might roll off better than wicking into the T&G or the screws--?
if it's just a few screws---maybe they aren't tight.? remove-maybe wet the tip of the screw with (clean oil) reinsert.?.
|
|
Anonymous
|
# Posted: 21 Mar 2012 12:50pm
Reply
Is your T&G horizontal or vertical? Did you put your screws in the "V joint" (assuming there is one) near the tongue? Or did you put screws in the flat part of the boards? The screws should be up in the groove and almost hidden (depending upon the particular design of the boards). I expect that water is simply working its way around through the tongues and grooves and coming in. A bit late for you, but I wonder if putting a bead of good caulk or a strip of foam rubber in the bottom of the grooves as you are putting the siding up wouldn't be a good idea.
|
|
niceboy
Member
|
# Posted: 21 Mar 2012 06:09pm
Reply
T&G is horizontal, screwed in the middle of the board, and I'm fairly sure no water is coming in between the tongues as dampness is only against some of the vertical beams.
Might try painting the heads with some sort of sealant as sparky1 suggests. Don't get much rain here though, just occaisional downpours, and last lot has all dried up now - might be a while till I can see if it works.
|
|
|
MtnDon
Member
|
# Posted: 21 Mar 2012 06:18pm - Edited by: MtnDon
Reply
How wide is the T&G? Is it 1" or 2"? Usually if it is 1 x 6" or less all you do is nail through the tongue with finishing nails at an angle into the stud. I use galvanized air driven finishing nails for that sort of thing. Tongue facing up, the groove facing down. Usually the only place it is face nailed is the starter strip at the bottom and probably the last strip or two at the top. I have a shed wall like that; no water has ever leaked through. Mind you we only get 8 inches a year.
I just mention that for the next time, the next person.
|
|
jgiffi
Member
|
# Posted: 21 Mar 2012 11:46pm
Reply
Could you provide pictures of the intrusion you are seeing and we might be able to provide more insight?
|
|
niceboy
Member
|
# Posted: 22 Mar 2012 10:50am
Reply
Thanks for all your help. Hold fire till the weekend when I can get some pictures up for you.
Nic
|
|
niceboy
Member
|
# Posted: 25 Mar 2012 05:21pm
Reply
Hi - busy weekend with ill baby, finally got some time to post photos.
The first shows the cabin as a whole, and the red on the last indicates where I saw dampness on the studs.
As you can see from the two photos of the screws, the black colour is staining the wood, so I may end up changing all the screws.
I had a thought. 4mm holes were drilled in the T&G for the screws, so they are not tight fitting, except at the head. If I replace them with wider screws, might this help?
Where the cabin is tight against my balcony walls, I screwed them to the studs from the inside. Those are the countersunk holes you can see in the inside photo. I countersank them a fraction too deep though, as most of them just broke the surface on the outside, possibly letting water in? For these ones, I'm considering taking the screws out, squirting something (silicon?) in, then putting the screws back in.
Any other thoughts or suggestions well appreciated
|
|
MtnDon
Member
|
# Posted: 25 Mar 2012 06:15pm
Reply
What kind and size of screws are those?
|
|
niceboy
Member
|
# Posted: 25 Mar 2012 06:25pm
Reply
er, black ones
Sorry, really don't know, just picked them up at diy superstore. I think I assumed because they were black they were somehow treated to stop rust. Will pass shop tomorrow and have a quick look.
Anyway, 4mm (outside of thread) and about 35mm long
|
|
BlaineHill
Member
|
# Posted: 25 Mar 2012 09:48pm
Reply
I don't think the screws that were driven from the inside are the problem, even through they did over-penetrate a little. Looks like the problem is the 4mm predrilled holes in the T&G. I think the screws driven from the outside and attached to the vertical board seen in the "inside" photo are letting some water in behind that board. You will probably want to pull all of those out, one at a time, fill the hole with a sealant and replace the screw with an exterior screw. I would look for screws that are recommended for decks and avoid screws recommended for drywall. Fair amount or work, but it shouldn't cost too much. Good luck with whatever you decide. Cool little place.
|
|
neb
Member
|
# Posted: 25 Mar 2012 09:58pm - Edited by: neb
Reply
You need galvinized screws that is why the bleeding is happening.
|
|
MtnDon
Member
|
# Posted: 25 Mar 2012 10:21pm - Edited by: MtnDon
Reply
To prevent the streaking you need a coated deck screw like the ones that are made for PT wood, or stainless steel. The gold zinc plated deck screws will also steak after a while.
If you use a sealant in the hole and insert a new screw the potential problem I see is that the sealant may squeeze out around the head. That will then be visible or affect how the wood weathers and/or accepts any finish product.
The best screw would also have a smooth shank near the head that is long enough to pass through the T&G freely and then threads after that. Screws like that will cinch the T&G down to the stud best. The smooth shank should be a little larger diameter than the holes you drilled. 4 mm is about the size of a number 7 screw; a number 9 would fit tighter. You might have a problem getting the length you need to prevent the point from driving through. You could always strap a piece of 1x material onto the inside of the stud for more thickness.
Screws through the thicker stud and into the thinner T&G is not a good idea.
A solution that would be a tremendous amount of work would be to remove all the T&G on one side of the building (one side at a time). Then apply a strip of flexible window flashing like Grace Vycor Plus to each stud face. Then reapply the T&G. The Vycor is a rubber material that will seal the screw holes. The narrowest it comes is 4 inch so you'd have to split it. Kind of a messy sticky job. There are other brands but Grace is the stickiest in my opinion.
|
|
niceboy
Member
|
# Posted: 26 Mar 2012 08:17am
Reply
Ok. I've got some 5mm zinc coated screws, and plan to replace all exterior screws with a little sealant in the hole. Any thoughts before I go for it?
The T&G was only screwed from the inside where necessary due to the proximity of the balcony wall. Hopefully these are not causing a problem - over-penetration was by 0.5-1mm only and not on all screws. However, some of the dampness was seen on the stud shown in the photo, which has been screwed from the inside. With luck though, it was running down from above, where the screws are on the outside.
Either way, I'll replace the exterior ones first, and see what happens.
Thanks for all your support
Nic
|
|
niceboy
Member
|
# Posted: 2 Apr 2012 07:39pm
Reply
job done - rain forecast for Easter, while I'm on holiday. May be the last we see until August.
I'll post again when I get some results...
|
|
niceboy
Member
|
# Posted: 28 Apr 2012 04:38pm
Reply
Seems A-OK now. Some of the water, I'm sure, was coming in through a window edge that I'd forgotten to seal properly - doh!
Anyway, those black screws needed changing to stop them staining my wood.
Thanks for all your input
|
|
|
