Observatory repairs and re-conditioning

[Gina]

As I posted in another thread, when I came to looking at my observatory in preparation for astro imaging after a long break, I have found at least one fairly urgent repair job.  The photo below shows the main problem - disintegrating plywood in the SE corner of the roll off roof.

[souls33k3r]

ouch! i hope it's not too much of work for you Gina.

If you had lived any closer to i am, would've given you a hand with the repairs.

[Gina]

Thank you - I expect I shall manage.  If I have any problems, I have great neighbours the would help if asked.

I was able to pop out to the observatory this afternoon and have another look.  The plywood has pretty much disintegrated in a small area and the EPDM rubber is wet underneath - I was able to pull down an area of wet, soggy plywood several inches wide and a couple of feet long.  Looking on top I can't yet see where the wet is getting in but it's more than wicking - there was wet on the floor in that corner, though not much, so it's not a big leak considering all the rain we've had lately.  I could see that the rubber is no longer glued to the plywood all over.  I shall have to have the barge board off that quarter and the batten off the end of the roof above the guttering so that I can fold the rubber back and see what I can see.  That will need reasonable weather but at least the forecast is better for next week (if that means anything).

[Carbon Brush]

Hello Gina. Is there standard roofing felt on this?

The reason for asking is that you are obviously going to have to strip the roof.

When I built my observatory I took the (at the time) very unconventional approach of using butyl rubber pond liner instead of roofing felt.

11 years on. Still waterproof. No signs of impending failure.

By comparison, other garden buildings using roofing felt have running repairs and in the summer I really should get some pond liner.

[Gina]

The roof is covered with EPDM rubber roofing which was originally glued down to marine ply with water based adhesive as recommended  and supplied with the EPDM but has become detached over the SE corner at least.

There are a few more smaller jobs I shall do when the weather is better.  The roof will open, though not as easily as it did.  There are also some minor leaks I can fix.

[Carbon Brush]

Aha. Your prompt reply anticipating my question!

When fitting my roof, I relied entirely on glue on the upper surfaces. No nails or anything else through it.

You will find staples only where the rubber has been tucked underneath in the dry.

[Gina]

Same here except that the barge boards are screwed through the vertical surfaces. 

[LightBucket]

I wouldn’t have thought that marine ply would have disintegrated that quickly to be honest..... ?

[Gina]

I don't know now long it's been wet - the observatory is 7 years old.

[Davey-T]

Not sure how waterproof marine ply is or waterproof board as they optimistically call it 

I have an 8 x 4 sheet that hinges up to block out an annoying street light and it's slowly delaminating as water penetrates the edge, I was going to paint it when I put it up a few years ago but never got round to it 

Dave

[Carbon Brush]

Would that be marine ply, or chinese marine ply?
Sorry to insult product from a particular country, but it pays to check.

I have bought marine ply in various thicknesses for various jobs in the last couple of years.
My local timber merchant has standard marine ply and lower price chinese marine ply.

Generally I have paid the extra couple of quid for the proper stuff and have been pleased with the results.
However, a communication slip led to me getting the chinese product once. Never again.

In places the cheap stuff had voids. It also suffered delamination after sawing.
As it was a non critical dry application I lived with it. Clamping and gluing some delamination, but binning other parts.

Gina.  If you get a tarp big enough to cover the roof and at least part of the walls it will give you an opportunity to prevent further damage.
Use the loops and rope to fasten it to the gound, or even screw into the shed sides.
It will also give you time to assess damage and consider the solutions.
I did this on a big shed rebuild while I got the new roof ply and rubber sheet organised.

Good luck with the repairs.

David.

 

 

 

[Gina]

I did have a big enough tarp but it's got holes in now.  If the weather forecast is right I may be able to start the job on Sunday or maybe even tomorrow.  I don't think a few days is going to make any difference.  I think this was proper marine ply which I got from my local timber merchant but can't be sure as it was 8 or 9 years ago.

[Astrokev]

All the best with root-causing the problem Gina. It's foolish for me to speculate what may have gone wrong but I hope any required repairs are fairly straight forward, and that you can soon return to more enjoyable projects!

[Gina]

Thank you.  I should know in a couple of days or so.  I'm not afraid of it and not particularly worried about putting it right - I like working with wood.  I have some of the 6mm marine ply around and hopefully a big enough piece to effect the repair.  I could always add some extra support members if necessary.  As for more enjoyable projects, I do these in between observatory repairs ?  I've been working on my widefield imaging rig and replacement all sky camera, plus Mini 3D printer upgrade.

EDIT - NOT repeat not afraid of it.

[Gina]

No joy with the weather today but it's looking better for tomorrow so I'm hoping to examine the damage and maybe find the cause.  OTOH if there's still showers about I should still be able to get out to the observatory and check a few things.

[Gina]

The weather forecast is for showers again today - the weather seems to be one step ahead of me as each day goes by!!  I shall be out there though having a look even if I can't risk taking the battens off to lift the EPDM.  At least the strong wind seems to have gone.

[reezeh]

Ouch Gina! ?

 

As as some peeps on here know I've recently got my paws on a catsperch chair and I'm not going to let it out of the house until I've added protection and grip to the feet. I'm considering using some stuff, I believe made by Ronseal called Isoflex which is essentially paint-on liquid rubber that's used to seal flat roofs to provide the sealant (needs their primer too) and maybe a layer or two of old inner tube. Maybe Isoflex is good for you too here.

[Gina]

The sun is out ATM but showers are still forecast and I've been out to the observatory and opened the roof.  Removed the batten holding the EPDM above the guttering with hammer and chisel, being careful not to damage the EPDM and lifted it to reveal some very wet rotten plywood, most of which I've removed.  No sign of how the wet is getting in - the EPDM is intact and in good condition.  The adhesive used to attach it is still on the plywood but separated from the EPDM over most of this side of the roof as far as I can see.  I have taken some photos which I'll post shortly.

I don't think there will be any need to remove the SE barge board holding the EPDM as I can lift it sufficiently to replace the rotten plywood.  This is good as the ground is very wet and soft and doubt I could use a step ladder outside to get at the screws (and I'm not climbing onto the roof to get at them!!!).  Since I can't find where the wet is getting in, I think I shall just insert a sheet of acrylic (waterproof and rotproof) between the EPDM and the present plywood, at least as a temporary measure.  It's too cold to spend long periods outside - my fingers nearly dropped off!!  And gloves are too awkward.

[Gina]

Here are the photos.

[Dr_Ju_ju]

Did you leave the hammer under the EPDM as well ? ??

[Gina]

No!

[Dr_Ju_ju]

ROFL, it just looks like its seen some rough weather as well.....

[JamesF]

I't's hard to see how water can have got up there.  Has the EPDM been sitting in the gutter?

James

[Gina]

Yes, it has.  Do you think that might be the problem? 

Actually, I'm not sure guttering is actually needed.  The idea was to stop rainwater from going underneath the observatory but I think the amount from half the ROR would be negligible compared with the amount coming downhill off the ground.  Of course, it also save some wash down the east end when the rain is from an easterly direction so I guess I should reinstate it after roof repairs.  I might replace that mini guttering with full size.

[Astrokev]

In my build, I have the EPDM hanging into the gutter by design. I wonder if water is likely to track up the inner surface? I wouldn't have thought water would do this, as EPDM has no wicking properties, but I wonder?

if the edge of the EPDM is dangling in water and it CAN wick up the inside then there's a risk it will reach the timber frame and soak into that. Over time this would probably get into the ply. 

Could this be happening? If so then I ought to trim my EPDM back a bit to avoid immersion in standing water