Builders of the org, decking balcony

[Brettus]

This latest hare brained idea is likely to die on the drawing board before apathy even gets near it but here goes.

I've got a flat roofed bathroom stuck on the back of my house, I'd like to ideally make use of that flat surface by having a garden deck. My theory is that I could stick pergola posts against the walls to raise it above the flat roof by a few inches and have a deck at around 260cm, it would be max 3m on each side with some balustrade.

Access I'm not sure about as the house is at different heights so I'm not sure I could put a door in on the second floor even if I actually made this but I could in theory have external steps up to it.

The eventual idea would be something like this:
http://www.evergreengardenskent.co.uk/fpss/slideshows/Decking/images/deck_02.jpg
just built over an existing bit of house so no dark area like that.

Perhaps with a small section of clear corrugated plastic to give an outdoor covered area.

I'm assuming that planning laws would mean I'd need permission for something like this but I seem to recall timber structures having some certain caveats. Although I suspect the height thing would raise some eyebrows.

Any advice/mockery welcome :-)

[AndyBrad]

You need owenski

Sent from my HTC Desire using Tapatalk 2

[Specialone]

Pretty easy to do, I'd try and put a doorway through though rather than steps tbh.

Main thing is it will need to be raised to allow water to pass under the deckboards.

[Stephen McG]

Took me a while to understand what you want.
I suspect that the existing flat roof was designed for snow/wind/maintenance (i.e. 1 man up there)
How do you know that it will take many people moving around - maybe dancing.
Building control will specify a steel beam arrangement to keep new load off existing roof.
Sorry.
PS where is the photo from?
I cannot see bracing to carry sideways sway.
Unless there are large gusset plates hidden behind the facia at top of columns,
that is unstable.
SMcG in Glasgow

[MisterTommyH]

If you're not going to have that kind of height on the legs i.e. just stub columns, then It might not be too much of a problem.

Your existing roof almost certainly won't be designed to take the additional load of the decking or the access (live) loading - and probably wouldn't cope too well with point loading from posts, but if you can determine where the load bearing walls are (which way the joists span) then you could either put posts directly above the walls, or run a spreader perpendicular to the joist right next to the support assuming you can't get right over the top (this shares the load and applies it in the place with least detrimental effect).

SP1 is right that you'd want it raised to allow water to run off, but you may also want some way to access it to clear off vegetation or to allow repairs to the asphalt (remember flat roof waterproofing only has a design life of about 10 years).

I would have thought that the biggest issue with planning would be to do with lines of sight etc... i.e. would that terrace put you in a position where you take away someone elses privacy. Building control shouldn't have too much of an issue with it providing it's done right and won't be specifying anything (not their job). Stability certainly shouldn't be an issue.

Edit: There was a recent NHBC article / study where they concluded that they would not pass / warranty an external timber raised (more than 1.5m). Doesn't mean you couldn't do it on and existing property under LABC, just that it's recognised as not being great (and the NHBC are all about **** covering) - anyway while that applies to the photograph, it doesn't to your idea which would be off a (presumably) masonry structure.