Roof Terrace..

johnonymous

I have recently had an offer accpeted on a Victorian terrace with a flat roofed extension. The roof is not overlooked at all owing to much higher walls on two sides and a fence up a steep hill on the back. The house has what is euphemistically reffered to as a courtyard garden but is really just an alley between the extension and the main house. I have found some amazing foldaway stairs that would allow me to get up there without killing the light to the main building so the only impediment to the project is the strength of the roof. Does anyone have a rough idea of how much the roof strengthening migjt cost if it proved to be neccessary?

Jeepers_Creepers

Almost certainly it'll be a 'proper' roof, so fully capable of carrying the weight of a few bods. Provided you don't all stand in one place and jump up and down.

A 'lightweight' roof should have warnings signs to this effect - use crawling boards or similar.  But it's no guarantee it ain't one if it doesn't.

When was the extension built? Do you have any details of this - plans etc? Or, can you find it on the LA's Planning Portal? That would hopefully show you the plans and design used, and will give you a very good idea of just what you can do up there.

A connected issue is, what finish does the roof have - what type of covering? Some are really not designed for traffic.

What do you actually want to do up there? Just sit on a beanbag? Or deck it out, build a BBQ, plonk down a jacuzzi? (We've had a flat-roofed extension built, finished in GRP and the upstairs bedroom's French doors happen to lead out on to it. We just take beanbags out, tho'.)

To strengthen the existing roof would be not far away from rebuilding it - a mega job. Whether something can be contrived to suspend a new 'floor' above the existing roof by taking posts up from the walls or similar, I dunno.

What size is't?

johnonymous

Thanks for the reply, I am not sure when the extension was built but will look into it. It is about 5m by 4m and has a felt roof. All we are really looking to with it is put two chairs there and decorate the fence with a lot of vertical plants, maybe artificial otherwise there might be an issue with them draining onto the roof. Interesting to hear that you built doors onto your terrace, I was thinking that if we ever come to sell the place we might be forced to take the stairs down as they imply the roof is suitable as a full living space. A jacuzzi would be nice! But I am thinking that as strengthening the roof involves a rebuild then we just go with using the space as much as the current set up will take. We are going to be knocking a wall out to make one room out of the dining room and living room

so the builder can probably advise us on the roof then.

grumbler

For walking and furniture you need some harder cover than felt or similar. And it has to be light enough.

Composite decking?

johnonymous

That is something I would love to put up, but  was unsure about whether it could be done. After spending half an hour reading on the subject I thought that decking required building regulations, which in turn required balconies (not a problem) and an adequate roof strength; which is either not a problem, or makes the whole thing cost prohibitive. As a side note I am happy with the property on the assumption that the roof space is unusable, would just be a nice bonus.

Jeepers_Creepers

johnonymous said:

Thanks for the reply, I am not sure when the extension was built but will look into it. It is about 5m by 4m and has a felt roof. All we are really looking to with it is put two chairs there and decorate the fence with a lot of vertical plants, maybe artificial otherwise there might be an issue with them draining onto the roof. Interesting to hear that you built doors onto your terrace, I was thinking that if we ever come to sell the place we might be forced to take the stairs down as they imply the roof is suitable as a full living space. A jacuzzi would be nice! But I am thinking that as strengthening the roof involves a rebuild then we just go with using the space as much as the current set up will take. We are going to be knocking a wall out to make one room out of the dining room and living room

so the builder can probably advise us on the roof then.

We had the French doors first, with a glass panel for safety on the outside. When we converted the loft over 10 years ago, we had them fitted as we wanted large opening doors for summer breezes and the voos. Last year we had the extension, so the glass panel came off and outdoor beanbags were bought...

4m x 5m is pretty big. Before even thinking about putting anything on there other than yourself and a beanbag, you need to find out what joists were used (presumably going in the 4m direction) for a guide to how strong and sturdy it is - you also don't want even small movements which could causes cracks in your ceilings below.

And, as mentioned above, felt is tough stuff, but is not designed for regular foot traffic. Also, composite decking is heavy - as I've just found out.

weeg

Turning in to a 'proper' terrace would need full on building warrant and probably roof strengthening. A jacuzzi is a definite no. (It's a long held ambition of mine to put one on my roof. Still working on it!)

That said, roofs are designed for occasionally foot traffic/ maintenance. So a couple of folk and deckchairs isn't going to be an issue. More than that, talk to an engineer.

johnonymous

Jeepers- Ah now I understand the French doors, sounds like an awesome roof you have going on there!

Weeg- I was not really serious about the jacuzzi; keep working on it though that would be amazing!

It seems likely we will stick at a couple of chairs, still a big upgrade over the courtyard garden to sit in, good to know that we are not going to be falling through to the dining room!

Jeepers_Creepers

I'd get some wide pads to sit the chair legs on, especially in warm weather - felt softens easily, and a normal chair leg will almost certainly indent it - at least.

Tbh, you'd probably be perfectly ok with laying a small area of decking tiles straight on, but don't go crazy... This will protect the felt.

Make sure they have flat bottom slats to spread the weight - eg: https://www.wickes.co.uk/Wickes-Softwood-Deck-Tile---400mm/p/223455

I'd also imagine you'd be safe with plant troughs for some greenery up there, provided you run them near the perimeter where the bending force will be minimal. Again, make sure there are no narrow/sharpish legs on it.

weeg

Jeepers_Creepers said:

I'd get some wide pads to sit the chair legs on, especially in warm weather - felt softens easily, and a normal chair leg will almost certainly indent it - at least.

Tbh, you'd probably be perfectly ok with laying a small area of decking tiles straight on, but don't go crazy... This will protect the felt.

Make sure they have flat bottom slats to spread the weight - eg: https://www.wickes.co.uk/Wickes-Softwood-Deck-Tile---400mm/p/223455

I'd also imagine you'd be safe with plant troughs for some greenery up there, provided you run them near the perimeter where the bending force will be minimal. Again, make sure there are no narrow/sharpish legs on it.

Those decking tiles look ideal. If it helps, roofs need to be designed to take minimum 60kg/m2. Floors are 150kg.

I'm lucky enough to have a 'proper' roof terrace, so I reckon I can make a hot tub work, weight wise (with careful positioning and spreader plates). It's the plumbing and the crane hire I need to deal with! 

johnonymous

Thanks,the advice is much appreciated, those decking tiles would look great.