Are flat roofs guaranteed to leak ?

GreatOaktree

Imagine a single story extension on a two up two down stone farm house. The extension ceiling is only about 2 foot below the upstairs window leaving me with 3 options:
1. move the upstairs windows up into the roof dormer style.
2. have a very shallow slope roof which will be ugly as hell.
3. A flat roof which could double as a balcony allowing me to sit out on a clear day and see halfway across the county to the mountain (glorified hill) close to my home place. It would have to be large (100m square). So my question is, Is it guaranteed to leak ? what would be the construction method considering I want a tiled finish eventually ? would tin be less likely to leak than the torch on or glue down material ?

Bonzo Delaney

You could look at the fibre glass option with a warm deck roof.
The build up would be
18 mm osb board
100-150mm insulation board
18 mm osb
Fibre glass 8mm roughly.
And a fall of 1:60 using firring pieces.

cork2

No at all, flat roofs are put on building everyday very successfully too! There are a range of options Fibre glass, asphalt, single ply membrane and torch on felt. For me torch on felt is a no no. If it was me I'd go for asphalt, it's not cheap but it's a quality job! Pick a material, select a specific brand and get a reputable installer and a product manufacturers guarantee.
This is just a few options but if you're doing an extension in this day and age there will be an engineer involved and an individual assigned to over see the build they will give you the information needed, but a flat roof is a perfectly viable option.

Triboro

cork2 wrote: »

No at all, flat roofs are put on building everyday very successfully too! There are a range of options Fibre glass, asphalt, single ply membrane and torch on felt. For me torch on felt is a no no. If it was me I'd go for asphalt, it's not cheap but it's a quality job! Pick a material, select a specific brand and get a reputable installer and a product manufacturers guarantee.
This is just a few options but if you're doing an extension in this day and age there will be an engineer involved and an individual assigned to over see the build they will give you the information needed, but a flat roof is a perfectly viable option.

Whats involved in the asphalt process and does it just go on marine ply , osb or what?

cork2

Triboro wrote: »

Whats involved in the asphalt process and does it just go on marine ply , osb or what?

You'd have firring pieces on top of your joists to create the falls in the roof, then a deck of osb or wbp, I generally use t and g osb, in this scenario marine ply is a waste of money. Then they roll out a vapour control layer, put the insulation on top of that and pour the asphalt out on top of the insulation. The insulation has a special layer on the sheets to take the asphalt. That leaves you with an asphalt warm roof.

TheLastMohican

Try looking for a roofing specialist firm that guarantee it not to leak

But seriously, in this day and age a new flat roof should be OK if the plans are right and the work is done right. After all, structural faults should be at a minimum as the heat/cold span is not too great.

iano.p

A roof that is put up cheap or by someone that isn't great at there job is going to leak. But shop around there is loads of great companies doing flat roof that will stand over there work if something went wrong.