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Raising the height of a flat roof


Jml

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I like to know how things fit together.  After a few hours looking at numerous google images none of which seem to represent a design similar to our extension, I need some help! It probably obvious but I’m flummoxed.

 

Our extension will have part flat, part pitched roof attached to a pitched roof of the main house.  The flat roof joists I assume will sit on or hang off the wall plates, which will also support the pitched roofs.  If we wish to have a higher ceiling under the flat roof part, the flat roof joists need to be lifted up how is this done?

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Depends on the height of the wall where the pitched roofs are, and if you need planning to change it. 

 

You could just do another pitched roof parallel to the main one with a valley but that would need PP I expect. 

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C894BE15-8987-431B-9303-887030B9100E.thumb.jpeg.10cd84fe25950664f7094ffcefe25f55.jpeg

 

Ignoring planning (at the moment), in the diagram abovethe shaded walls would have to be raised?

 

What then happens to the piched roof next to it?  Does the ridge move or the roof become uneven or do you have to raise the left hand wall of the pitched roof?

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You could do it like this pretty easy.

Depending on how you want it to look on the inside you could put a fancy ridge beam in from the new peak to the existing roof on the left and have it exposed or not. Depending on what is at either side of you and depending on planning you could put a skylight or two in.

DrawOnPhoto_1509563072723.png

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Or go crazy and have pitch at the top and at the left and have the square area as a flat room giving an area of high ceilings in the extension.  I have a bungalow with high ceilings that slope from 2.4 to 3.6 metres high, marks an amazing different to the feel of the rooms.

Or that area I've drawn could be sloped from the ridge to the bottom all the way across

IMG_5953.PNG

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Essentially idea never occurred to us!

Something to think about!

We had idea of flat roof with number of large skylights, to let light into centre of house. Roof on left we plan to have as vaulted ceiling, essentially replacing existing flat roof extension, new part of extension is the flat roof part.  Not sure we could afford to do two vaulted ceilings, but suppose we could look at rooflights or compare the costs of the two.

Is there any potential problem with the v shaped valley between the two piched roofs?

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28 minutes ago, Calvinmiddle said:

Or go crazy and have pitch at the top and at the left and have the square area as a flat room giving an area of high ceilings in the extension.  I have a bungalow with high ceilings that slope from 2.4 to 3.6 metres high, marks an amazing different to the feel of the rooms.

Or that area I've drawn could be sloped from the ridge to the bottom all the way across

 

 

Many thanks for the ideas, seems we have been bit uninventive!  We unfortunately have a rear dormer which I missed from the drawings on the right hand side, for an upstairs man-cave, so your last idea probably a step too far, but certainly consider double pitch as no fan of flat roofs, ours at moment are leaking like a sieve!

Oops. Would have to see if we can work double pitched roof around dormer also!

Edited by Jml
Too much wine and not thinking clearly!
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either a pitched roof parallel to existing, does leave a valley which is no big deal other than collects leaf and moss and needs cleaning out. my preferable option would be a pitched roof across both new parts at 90deg to existing roof.

edit. post above posted at same time. dormer could cause problem

Edited by Simplysimon
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Think will have to make an effort to get rid of the flat roof if we can! Scale of my sketch was pretty rubbish, just checked dimensions and piched roof approx. 5m wide and flat roof 13m with a rear dormer to work around, so will need some thought!

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15 hours ago, Tennentslager said:

Pictures would help too?

 

See below, at least these are to scale, and include the dormer which had merrily forgotten about yesterday!

14 hours ago, AliG said:

Depending on the interior layout rather than raising the roof you could do a room under it with a step down into it, I think that is the normal solution to this kind of situation.

 

Had though about that, not a great fan of a step especially as our plot is pretty flat. We would also have to dig up part of existing flooring which would form part of the new kitchen diner and as we are building over a mains sewer (unfortunately) I want to keep as far above that as possible to get permission from Thames water.  Would certainly be a neat soultion though.

 

 

 

 

 

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Edited by Jml
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Build a steel frame outside the existing exterior walls to support the flat roof that is higher than the current wall holding up the pitched roof. Then have the flat roof overhang this until it meets the pitched roof. I would guess that although you need a wall to support the flat roof the small width of the overhang could be supported by the existing roof trusses.

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3 hours ago, AliG said:

Build a steel frame outside the existing exterior walls to support the flat roof that is higher than the current wall holding up the pitched roof. Then have the flat roof overhang this until it meets the pitched roof. I would guess that although you need a wall to support the flat roof the small width of the overhang could be supported by the existing roof trusses.

 

Makes sense.  Could you build up the wall between the pitched roof trusses to do the same thing?

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