Dampness

[Astroscot2]

Hello all.

I have a home made wooden Ro-Ro observatory for a couple of years and this year has been a particularly wet winter in the West of Scotland, Last winter I had a small issue of dampness in one corner of the observatory, during last summer I took off the wooden corner trims, silicon sealed all the edges and gave the whole observatory 4 coats of ducks back. I also made covers over the small gaps where the front of the roof meets the runners, also little overhangs to divert water away from the main building. All seemed well…

I’ve hardly used the observatory in over 6 weeks and got a bit of a shock a few days ago to find that water has made its way in through all 4 corers with the inner OSB a bit damp.

Can I ask how other members are waterproofing the corner edges of their wooden observatories; I’ve searched the internet for some sort of rubber trim but can not find anything. I have a dehumidifier currently running but that’s not going to stop water getting in.

Appreciate your thoughts.

[Merlin66]

Usually it's the vapour barrier which keeps the majority of the moisture out - and the inside dry.

Does your vapour barrier continue around the corners??

[malc-c]

can you give any idea of how the obsy is constructed. Apart from the DPM on the dwarf wall that supports the floor hangers I haven't used a barrier and both obsy and warm room have been damp free.

[Astroscot2]

No vapour barrier, OSB on the frames, 16mm shiplap over the OSB which overlap at corners, wooden trim on corner edges...Its only the edges where the dampness is showing, im sure there must be a product that can seal the corner/edges?

Mark

[laser_jock99]

Could you re-skin the entire obsy in steel cladding panels (like wot I used as an inner skin)? They don't let any water in.

[Astroscot2]

I wonder if just the corners could be purchased ?

[laser_jock99]

I wonder if just the corners could be purchased ?

Yes- they go under the name of flashings:

Flashings | Rhino Steel Cladding

Box Profile Roof/ Roofing Sheets and Cladding FLASHING | eBay

[noakesy]

ive a wooden obsy ,, i painted mine with rubber paint from b and q used on felt roofs works well no water gets in ,, and weve had some bad weather

[Astroscot2]

Thanks for the info and links folks. I considered the rubber paint too, doyou have any details on the brand you used. I presume you used it just on the corners?

regards

Mark

[Helen]

I'm watching this thread with interest as I have the same problem (and mine lead to a complete rot through in the corner.

Helen

[Freff]

I have just helped a friend with his obsy with the same corner problem.

The way we solved it was by filling ALL the end joints of the shiplap where they butt. Use a flexable frame sealant not silicon. Then the area coated with whatever the obsy is finished with.

The corners were then clad with 3"x 3" x .75mm 'L' shaped steel.

For belt and bracers we then filled all the curved recesses in the shiplap left by the 'L' cladding with frame sealer to prevent water running in behind the steel.

Hope that makes sense. I can post an image if it helps.

[Freff]

I have just been down to my (unfinished) obys to take a few photos of what I mean above.

Although not fitted yet, I intend to fit corner cladding mainly as a protector against knocks from bikes, wheel barrows etc to my obsy. These will be fitted after the final painting.

Anyway, I put a corner piece in place just to help explain how I overcome a friend water ingress. It appears to be working OK to date after all the bad weather we have had, and even a high pressure water hose played on the areas had no effect.

[Astroscot2]

Thanks Tony, another good solution, If you can post images that would be great.

thanks

Mark

[Astroscot2]

Just seen the images Tony... What is corner cladding if you dont mind me asking ?

[Gina]

I used corner timbers with the ends of the shiplap butted up to it with frame sealer applied where needed.

[Freff]

Just seen the images Tony... What is corner cladding if you dont mind me asking ?

I used the same material as my roof. It's pieces of painted galvanised steel 0.75mm thick bent at 90° 2 1/2" x 2 1/2" in my case.

[ollypenrice]

Is there any way to give the roof more overhang?

And do you have gutters operating?

Mine is mainly breeze block but I have gutters on both the fixed and moving parts, pror to which a lot of water ran down the outside walls and also puddled beside the building. This no longer happens.

Olly

[Freff]

I used corner timbers with the ends of the shiplap butted up to it with frame sealer applied where needed.

Fortunately Gina you were wise enough to use a vapour barrier, which should stop any water that passes those joints.

My mates obsy didn't have a barrier and was finished like yours with the shiplap butted against corner timbers. Unfortunately, shiplap in 5 mtr + lengths tend to expand and contract slightly even if they seasoned well.

The water got in and damage done.

Now it's sealed with a good frame sealer, which I feel adheres to treated wood better than silicon and can be over painted with wood preserve or paint.

[noakesy]

i used bathroom seleant to seal the corners of my obsy then painted it with rubber paint

[Gina]

I used the stuff designed for the job "Frame Sealer" this is designed for wooden window and door frames, sticks to the wood (even treated) and is flexible and never hardens completely. It's readily available from most DIY shops.

[laser_jock99]

The belt & braces approach is best. Two skins/wall layers is best- an outside layer to hold the worst of the weather and a liner layer to keep dampness out. Barge board corner flashings keep rain penetration at the corners to a minimun and some form of sealant (I used flexible fram filler as well) finishes the job off.

Allow a large overhang on the eaves and this will keep the worst weather from runing straight down the walls. I used nearly a 12" overhang- not seen any rain running down the outer walls yet. Must say I'm really impressed with the steel cladding- all the outbuildings round here seem to made with it.

Overhang.

[Aoraki]

I've used this on the walls that I couldn't posibly attend to if there were problems, unattractive but good.

[Freff]

I've used this on the walls that I couldn't posibly attend to if there were problems, unattractive but good.

That's good stuff, and what the eye can't see......

[Aoraki]

And it sticks like sh.... petrol soaked rag to clean the hands after!