Gina's Observatory

[Gina]

Hi Gina, Regarding the gale-proofing ideas. When I built mine I made it so the RoR when closed has 2 long bolts that go through the matting warm room wall and 2 at the end wall - I simply use wing nuts on these bolts to secure the RoR to the obsy structure...

That sounds nice and simple I like "nice and simple" in spite of what people might thing from my design

[malc-c]

Gina, I personally think you are over engineering this. Yes the Rubber EDPM concept is nice, but to shell out £200 just to cover the warm room IMO is OTT.

A decent heavy grade felt will last 20 years... (our house is a shallow pitched roof with felt covering, last covered 12 years ago and recently inspected - estimated life left 7 - 10 years). OK I used the heavy grade stuff from Wickes on my observatory, but you can buy cheaper - this came up in a google search UV25 Breathable Pitched Roofing Felt 1m x 50m (Roll) - £70 for a 50m roll - more than enough to cover the Observatory and warm room several times over

Sorry if my comments seem harsh.. I'm not wanting to offend but I think you are getting too wrapped up in the design and in turn escallating your costs accordingly.

[Gina]

Re. warm room roof...

This is an image linked from the Rubber4Roofs web site showing the use of their trims:-

This pic is evidently of a small mock-up model to show the features and could be a bit misleading. The side trims are 100mm high according to their site and thus the "kerbs" are about 25mm (1"). (Unless I've misread the web site.)

I'm thinking of just using the top and sides (with the top corners) and taking the bottom edge over the wood and up under to form a drip bar to discharge rainwater into the guttering. This will look neater (I think), save £40, and keep the current doorway height of about 6ft.

[Gina]

Gina, I personally think you are over engineering this. Yes the Rubber EDPM concept is nice, but to shell out £200 just to cover the warm room IMO is OTT.

A decent heavy grade felt will last 20 years... (our house is a shallow pitched roof with felt covering, last covered 12 years ago and recently inspected - estimated life left 7 - 10 years). OK I used the heavy grade stuff from Wickes on my observatory, but you can buy cheaper - this came up in a google search UV25 Breathable Pitched Roofing Felt 1m x 50m (Roll) - £70 for a 50m roll - more than enough to cover the Observatory and warm room several times over

Sorry if my comments seem harsh.. I'm not wanting to offend but I think you are getting too wrapped up in the design and in turn escallating your costs accordingly.

I always appreciate comments, both positive and negative, so no worries there

You may be right but I'm worried about sealing the top corners and the RoR to warm room roof join. I'm also not happy about felt joins with a very shallow slope. The roof kit on it's own costs £79.52 including delivery and VAT (not much more than your big roll of felt, and about twice the cost of a 10m roll of decent felt). Adding the side trims would add about £37. The top edge trim and corners a further similar amount. That's £155 for side trims, top trim and 2 corners.

The mould is not yet cast and I'm still considering options.

[Freff]

Good to see you have made more progress before the weather closes in.

Regarding the felt, you shouldn't worry about the shallow fall many flat roofs are done with felt. Just make sure the joints are are well overlapped and sealed with a hot pitch.

[Gina]

Good to see you have made more progress before the weather closes in.

Thanks

Regarding the felt, you shouldn't worry about the shallow fall many flat roofs are done with felt. Just make sure the joints are are well overlapped and sealed with a hot pitch.

Hmm... not sure I could cope with hot pitch 6 or 7 ft up in the air! Yes, I know many flat roofs are done with felt.

[Bizibilder]

I've just had a flat roof on my garage re-felted (admittedly by professionals) and the estimate is at least 20 years before it needs replacing (the old roof was 22 years old and it was only one part of one edge that had split). I think you will find that heavy duty felt will last 10-15 years on a flat roof if applied properly and glued down rather than nailed. Modern cold-working adhesives work well as long as you use the correct one!

[Gina]

I've just had a flat roof on my garage re-felted (admittedly by professionals) and the estimate is at least 20 years before it needs replacing (the old roof was 22 years old and it was only one part of one edge that had split). I think you will find that heavy duty felt will last 10-15 years on a flat roof if applied properly and glued down rather than nailed. Modern cold-working adhesives work well as long as you use the correct one!

Ah yes - the correct adhesive That sounds more like it But what IS the correct adhesive? A cold applied adhesive sounds fine, I guess you apply it with a brush. I know many of the DIY shops sell roofing adhesive but I suspect it's like wood treatment - some may be rubbish.

Have to say, I'm all for saving money as long as the end result is satisfactory. Money saved on the warm room roof means the sooner I can afford the shiplap and later on the sooner I will be able to afford my next scope

[Bizibilder]

Don't use a DIY shop - go to a proper builders merchant (with a decent reputation) and they should be able to advise you. (Then thank them and buy the same stuff cheaper on the web.... )

[Freff]

Thanks

Hmm... not sure I could cope with hot pitch 6 or 7 ft up in the air! Yes, I know many flat roofs are done with felt.

Gina I didn't mean the old way with a bucket of boiling tar and brushes. The modern felts have the pitch already on the felt, you just heat it with a blow lamp or powerful heat gun as it rolls onto the roof.

Providing the timber is dry and clean it will stick like the proverbial to a blanket.

[Gina]

Don't use a DIY shop - go to a proper builders merchant (with a decent reputation) and they should be able to advise you. (Then thank them and buy the same stuff cheaper on the web.... )

We have Jewsons and Bradfords in Honiton. I've generally found their merchandise to be pretty good. I guess Wickes own brand would not be recommended?

[Gina]

This is how I'm thinking of dealing with the edges (diagram not to scale) :-

[Aoraki]

Gina, your diagram above is how I'm thinking of triming my roof using the rubber roofing. I had looked at using the kerbs and corners from Rubber4roofs but it does add a considerable amount of ££. I think if the timbers for the trim are tanilised and a beading of good quality mastic/silicon applied to the rubber/timber joint I belive this will provide a quality roof at a reasonable price.

[Gina]

Gina, your diagram above is how I'm thinking of triming my roof using the rubber roofing. I had looked at using the kerbs and corners from Rubber4roofs but it does add a considerable amount of ££. I think if the timbers for the trim are tanilised and a beading of good quality mastic/silicon applied to the rubber/timber joint I belive this will provide a quality roof at a reasonable price.

Yes, agreed. I'm still undecided as to whether to use rubber or felt. The consensus of opinion seems to be to use felt.

Trouble is... there's felt and there's felt. It's being sure you have a good product. The best seems to use two layers - maybe that's the sort that lasts for 20 years.

[fwm891]

Gina, You might give yourself some long term problems with the securing batten sitting at the same level as the felt as water will 'wick' between felt and batten leading to possible early decay.

Just needs the edging raised slightly to avoid problems.

Francis

[Gina]

Gina, You might give yourself some long term problems with the securing batten sitting at the same level as the felt as water will 'wick' between felt and batten leading to possible early decay.

Just needs the edging raised slightly to avoid problems.

Francis

Thank you Francis Good suggestion.

[Gina]

I have a roll of felt but I don't know if it's suitable. It's marked Rose Roofing, 30Kg and fibre based bonding felt, 10m. I've tried Googling it but not had much joy. Anyone know anything about this felt? I'm reluctant to use something I don't know about on this job. It was bought a while back with thoughts of repairing the goat shed roof.

[Freff]

Hi Gina. The felt you have is probably a under tile felt, but not sure unless you could post an image of the surface and edge.

I would use a mineral coated felt similar to this. HP 350 Brindle Mineral Roofing Felt Pour & Roll 7.5x1m | eBay

The secret with felt is the folding at the edges and corners. Get that right and you'll never get any problems.

EDIT... this is the type of felt I used years ago on my workshop. http://www.ebay.co.uk/itm/Brindle-Red-Brown-MINERAL-TORCH-ROOFING-FELT-8x1m-/260817368793?pt=UK_BOI_Ceilings_Walls_Roofing_ET&hash=item3cb9ed36d9#ht_2097wt_1021

[Gina]

Hi Gina. The felt you have is probably a under tile felt, but not sure unless you could post an image of the surface and edge.

Hmm, I wondered if I'd got the right sort of stuff! I'll take photos and post them as you suggest.

I've never used roofing felt before and know absolutely nothing about it other than what I've found on web sites like Wickes.

I would use a mineral coated felt similar to this. HP 350 Brindle Mineral Roofing Felt Pour & Roll 7.5x1m | eBay

The secret with felt is the folding at the edges and corners. Get that right and you'll never get any problems.

EDIT... this is the type of felt I used years ago on my workshop. Brindle (Red/Brown) MINERAL TORCH ON ROOFING FELT 8x1m | eBay

Unfortunately both of those are collection in person only.

[Freff]

Unfortunately both of those are collection in person only.

Those two on Ebay are just example, you can get the same from most builders merchants.

[Gina]

Those two on Ebay are just example, you can get the same from most builders merchants.

OK, I see. We have two in the town, Jewsons and Bradfords, I'll try them.

[Aoraki]

Yes, agreed. I'm still undecided as to whether to use rubber or felt. The consensus of opinion seems to be to use felt.

Trouble is... there's felt and there's felt. It's being sure you have a good product. The best seems to use two layers - maybe that's the sort that lasts for 20 years.

Gina, for the small area you are talking about I wouldn't hesitate at the rubber solution, one piece, no joints, no brainer. I have just ordered my rubber and if you fit it as per the drawing above (FWM891) as I am, it's a very cost effective long term roof.

I've ordered a 3m x 5m peice and adhesives and p&p for £183.48 inc vat, or another way to look at it £12.20 per square metre. edit.. claim the vat back, it is a goat shed after all

[Gina]

Gina, for the small area you are talking about I wouldn't hesitate at the rubber solution, one piece, no joints, no brainer. I have just ordered my rubber and if you fit it as per the drawing above (FWM891) as I am, it's a very cost effective long term roof.

Yes, I think you have a good point. Certainly a simple solution and would save the effort of finding the right sort of felt, adhesive etc. and worrying about the joins.

I've ordered a 3m x 5m peice and adhesives and p&p for £183.48 inc vat, or another way to look at it £12.20 per square metre. edit.. claim the vat back, it is a goat shed after all

That works out pretty cheap. I guess you're getting a cheaper sq m rate because you're buying a bigger piece. Can't reclaim the VAT - we aren't VAT registered.

[Gina]

Hi Gina. The felt you have is probably a under tile felt, but not sure unless you could post an image of the surface and edge.

Hi Tony. Not taken any photos yet but I can tell you that the felt is black or very dark grey and has sand on both sides. The thickness appears to be about a millimetre. I'll probably take photos tomorrow. Some photos I've seen of shed felt seem to show one side as smooth.

[Aoraki]

That works out pretty cheap. I guess you're getting a cheaper sq m rate because you're buying a bigger piece. Can't reclaim the VAT - we aren't VAT registered.

The rubber is £6.20+vat per square metre no matter what quantity, I'd included adhesive, p&p and vat in the £12/m. I am vat registered but can't think how to possibly claim for an observatory in my line of work!