Roof design issue

Ginger83

Hi all
I would like to change this flat roof to a slate roof to match the extension to the left but as you can see I have an upstairs window in the way.
Any advice on design?

Extension.JPG

sydthebeat

Why do you want to change it?

Ginger83

sydthebeat wrote: »

Why do you want to change it?

Hi i have never liked the flat roof and would like to match house with stone cladding etc

Gumbo

I like the design.

But should you wish to proceed, planning required to bring the roof level up?

You could increase the height of the wall and relocate the window or use a Velux.

Do you have a budget in mind for these works?
Can’t see any change from €10k and I’m
Probably being a bit light with that figure.

Ginger83

Gumbo wrote: »

I like the design.

But should you wish to proceed, planning required to bring the roof level up?

You could increase the height of the wall and relocate the window or use a Velux.

Do you have a budget in mind for these works?
Can’t see any change from €10k and I’m
Probably being a bit light with that figure.

Hi the flat roof always gave trouble,for some reason the parapet wall is only a single leaf.

I had the idea of a four sided slate roof with one side falling back to under the upstairs window. Any thoughts?

Gumbo

Ginger83 wrote: »

Hi the flat roof always gave trouble,for some reason the parapet wall is only a single leaf.

I had the idea of a four sided slate roof with one side falling back to under the upstairs window. Any thoughts?

Yes I’ve seen the reverse hip being done to keep windows assessable.
I don’t like it personally.

Could you look at redoing the roof?
What’s the current build up and finish?

kippy

Lads if ye look at a few of the threads on costs, 10 k wouldn't get the design and planning work done on a job like this I'd say. Could be a very pricy job.

Fine Cheers

Would tend to agree about potential cost and is it the right thing to do ? Ok parapet wall would have been better with cavity but some vertical insulation will help. To be honest it looks to have potential for a roof garden / balcony by changing that window to a door ? (sorry) Not sure how 4 sided slate roof will look - I assume you mean like a pyramid. Tricky gutter detail between new and existing but can be done.

Ginger83

Gumbo wrote: »

Yes I’ve seen the reverse hip being done to keep windows assessable.
I don’t like it personally.

Could you look at redoing the roof?
What’s the current build up and finish?

The roof is 9×2 joists, 18mm ply, vapour, 100mm insulation then rubber finish but the extension is always freezing.

The builder appeared to have made a major error. The parapet is single leaf and there is a line of bridging on top of the inner leaf. The builder believed the insulation company was going to pump beads up to the deck but the beads finished at the top of the inner block so there is a nine inch empty space on all three sides.

They did a repair but no better. Maybe that's why I'm reluctant.

Gumbo

100mm insulation is not enough in my opinion.

Calahonda52

some questions.
what height is the top of the parapet over the finished roof?
How is the parapet capped?
how much room is there from under the sill of the upstairs window to top of finished roof?
how is the extension ventilated?

Ginger83

Calahonda52 wrote: »

some questions.
what height is the top of the parapet over the finished roof?
How is the parapet capped?
how much room is there from under the sill of the upstairs window to top of finished roof?
how is the extension ventilated?

Hi
1 block I'd say
There was standard wall cappings used but they were removed for safety reasons
The roof is 4-5 inches higher on the side with the double doors than the other side and there is still maybe 3 inches clearance under the cill
Window trickle vents

Ginger83

Gumbo wrote: »

100mm insulation is not enough in my opinion.

That would not surprise me with the experience with the builder.
What would you suggest?
I had a look at a few flat roofs and some seem to float in the air with no walls hanging out over the walls
I quite liked them, is that a possibility?

Ginger83

20201006_142021.jpg

Here's a pic

Calahonda52

Thanks for the answers.
not much room in 3" for a pyramid roof
what sort is the 100 mm insulation?

Roof look in good nick, so what issues were you having?

My thoughts are that you add more insulation inside

Ginger83

Calahonda52 wrote: »

Thanks for the answers.
not much room in 3" for a pyramid roof
what sort is the 100 mm insulation?

Roof look in good nick, so what issues were you having?

My thoughts are that you add more insulation inside

It's 100mm xtratherm but it seems to be serving no purpose as the nine inch space under the deck on the three sides is empty.
We can't heat it

Calahonda52

so it sounds like a poorly executed warm roof with a 9" thermal bridge with the outer parapet wall?

Have you any mould issues around the plasterboard at the walls?

Ginger83

Calahonda52 wrote: »

so it sounds like a poorly executed warm roof with a 9" thermal bridge with the outer parapet wall?

Have you any mould issues around the plasterboard at the walls?

mould.jpg
We do indeed

Calahonda52

what about around the ceiling perimeter under the flat roof?

Ginger83

Calahonda52 wrote: »

what about around the ceiling perimeter under the flat roof?

You can see spots on the walls but ceiling looks ok. During the repair the builder appears to have fitted a 50mm slab on over the original ceiling.

the_pen_turner

not sure thats a good idea.
you have a warm roof. everything below the insulation is 'inside'
if the insulation is in the joists then the roof is a cold roof and 'outside'.

now you have both but no ventilation in the middle.
im no expert on these flat roofs but i would like someone who is to comment on that

Could you take the flat roof off, build the walls up a tad, put a new roof on, turn the window into a door, and have a whole new 1st floor extension?

Would only be expensive if you engage all the professional bodies for every step of the way. I've seen my local council approve planning requests based on drawings that a child would do. So long as the general idea is presented they don't tend to bust your balls over it (may vary from county to county though).

kippy

Deleted User wrote: »

Could you take the flat roof off, build the walls up a tad, put a new roof on, turn the window into a door, and have a whole new 1st floor extension?

Would only be expensive if you engage all the professional bodies for every step of the way. I've seen my local council approve planning requests based on drawings that a child would do. So long as the general idea is presented they don't tend to bust your balls over it (may vary from county to county though).

That's not as straightforward or cheap as it looks.
You are delaing with having to replace a roof with a floor, adding another roof and all that goes with it.
Suggesting not engaging an architect or engineer for that is folly.

Ginger83

Deleted User wrote: »

Could you take the flat roof off, build the walls up a tad, put a new roof on, turn the window into a door, and have a whole new 1st floor extension?

Would only be expensive if you engage all the professional bodies for every step of the way. I've seen my local council approve planning requests based on drawings that a child would do. So long as the general idea is presented they don't tend to bust your balls over it (may vary from county to county though).

I am honestly not sure what to do.

I would well believe your comments on the council. This extension was built for disabled use and a grant was paid for it however the work was signed off without being checked.

Unfortunately now the council don't want to know, the builder says it's grand, the care team say their hands are tied and building control authority has declined an inspection so it just sits empty.

the_pen_turner

could you pump the cavity around the top

mickdw

No way would i go changing that to a pitched roof.
Redo the flat roof taking proper account of weathering / damp proofing with a well detailed insulation plan, and you should be good.
Its a very nice looking extension as is and works very well appearance wise.
Another issue to consider is whether you are getting cold air from the cavity of the main house being fed into the extension.
If you have partial filled cavity on the main house, id pretty much guarantee that this is a major cause of heating issue as your builder wasnt exactly concerned about the finer details it would appear.
Id stick will a new flat roof and finish it with a pressed metal cap for a simple appearance.

Ginger83

the_pen_turner wrote: »

could you pump the cavity around the top

No we have had the insulation company out and they can only pump block to block. This empty space is block to 9×2 bridging.

Ginger83

mickdw wrote: »

No way would i go changing that to a pitched roof.
Redo the flat roof taking proper account of weathering / damp proofing with a well detailed insulation plan, and you should be good.
Its a very nice looking extension as is and works very well appearance wise.
Another issue to consider is whether you are getting cold air from the cavity of the main house being fed into the extension.
If you have partial filled cavity on the main house, id pretty much guarantee that this is a major cause of heating issue as your builder wasnt exactly concerned about the finer details it would appear.
Id stick will a new flat roof and finish it with a pressed metal cap for a simple appearance.

What insulation plan would you recommend?

kippy

kippy wrote: »

That's not as straightforward or cheap as it looks.
You are delaing with having to replace a roof with a floor, adding another roof and all that goes with it.
Suggesting not engaging an architect or engineer for that is folly.

Oh it'd be a big enough job, but would be a much better use of the space. I still wouldn't bother with an architect or engineer though. Get a good builder that you can trust. Builders are at it all day, every day. If you get someone that's personally recommended honest they won't rob you blind, and they'll know how to do it without an instruction manual from an architect.


However, it seems the aesthetics aren't really the issue here, anyway. If I were you, OP, I'd re-do the roof (be less than €5k I'd say) and re-slab the inner walls with a decent insulated plasterboard. Should sort out most of your problems, I'd say.


For what it's worth (and i'm aware I'm gonna get a load of posts on how wrong this is) I have an extension with cavity blocks (not a cavity wall, just cavity blocks), and it's insulated internally with insulated plasterboard, around 50mm thick (I wanted to go thicker, but getting insulation was a problem at the time).


The ceiling was insulated and roof done by a local roofers (flat roof, felt).


The place is roasting after a few minutes of the heating being on, and if you knock the heating off, the heat holds for a fairly reasonable amount of time. The house itself is a cavity-wall build, and it has not gotten any colder with the extension being added on (we opened up the kitchen).


So with that in my mind, that I have a very comfortable extension with fairly low specs, I can't understand how yours is so cold. Is it void of any insulation at all? Did they just do a single-leaf wall, render the outside and plaster the inside, and skip the insulation step altogether?

the_pen_turner

Ginger83 wrote: »

No we have had the insulation company out and they can only pump block to block. This empty space is block to 9×2 bridging.

whats the theory behind that. is it moisture transfer they are worried about or ventilation.

could spray foam work instead like they do on a roof. that is regularly put around timber.

if not then the ceiling will have to come down and bridgers come out an insulation put in properly.
why didnt they take down the ceiling and fix it before putting up a new ceiling

mickdw

Ginger83 wrote: »

What insulation plan would you recommend?

Get a professional on board properly. Lack of a professional or a poor one is what has got you here.
Id be thinking strip roof, rectify detail around the parapet, warm roof and then rectify detailing where extension meets original to ensure the junction is right re damp transfer and also that stray cold air is not moving into extension.
In main house is partial fill cavity, you will need to have works done at the part that meets the extension - cavity pumping to the main house wall.

Ginger83

Deleted User wrote: »

Oh it'd be a big enough job, but would be a much better use of the space. I still wouldn't bother with an architect or engineer though. Get a good builder that you can trust. Builders are at it all day, every day. If you get someone that's personally recommended honest they won't rob you blind, and they'll know how to do it without an instruction manual from an architect.


However, it seems the aesthetics aren't really the issue here, anyway. If I were you, OP, I'd re-do the roof (be less than €5k I'd say) and re-slab the inner walls with a decent insulated plasterboard. Should sort out most of your problems, I'd say.


For what it's worth (and i'm aware I'm gonna get a load of posts on how wrong this is) I have an extension with cavity blocks (not a cavity wall, just cavity blocks), and it's insulated internally with insulated plasterboard, around 50mm thick (I wanted to go thicker, but getting insulation was a problem at the time).


The ceiling was insulated and roof done by a local roofers (flat roof, felt).


The place is roasting after a few minutes of the heating being on, and if you knock the heating off, the heat holds for a fairly reasonable amount of time. The house itself is a cavity-wall build, and it has not gotten any colder with the extension being added on (we opened up the kitchen).


So with that in my mind, that I have a very comfortable extension with fairly low specs, I can't understand how yours is so cold. Is it void of any insulation at all? Did they just do a single-leaf wall, render the outside and plaster the inside, and skip the insulation step altogether?

The builder definitely cut corners. For example his drawing claims a 110mm pumped cavity but it's 90mm and I personally don't think the blocks are sealed as the drawing claims 20mm nap plaster under white finish but it's not there. 2mm of the white stuff was slapped directly on to the blocks.

Ginger83

the_pen_turner wrote: »

whats the theory behind that. is it moisture transfer they are worried about or ventilation.

could spray foam work instead like they do on a roof. that is regularly put around timber.

if not then the ceiling will have to come down and bridgers come out an insulation put in properly.
why didnt they take down the ceiling and fix it before putting up a new ceiling

The beads are only suitable for block to block due to pressure when pumping.

Cost I'd say

the_pen_turner

Ginger83 wrote: »

The beads are only suitable for block to block due to pressure when pumping.

Cost I'd say

would it create that much pressure. a 9x 2 with even 3 gun nails on each side would hold an amzing amount of pressure. i cant see that being the reason

Ginger83

the_pen_turner wrote: »

would it create that much pressure. a 9x 2 with even 3 gun nails on each side would hold an amzing amount of pressure. i cant see that being the reason

That's what the insulation company said when they inspected.

the_pen_turner

Ginger83 wrote: »

That's what the insulation company said when they inspected.

thats fair enough

Calahonda52

Ginger83 wrote: »

That's what the insulation company said when they inspected.

the top 9", pressure, ****ox

chooseusername

Calahonda52 wrote: »

the top 9", pressure, ****ox

I'd say they didn't fancy pumping beads into a 9" high cavity not knowing the make up of the cavity.
Op says there is bridging but not what type.
Joists may be crossing the cavity
Also, if pumped insulation stopped at the top of inner leaf,
it means the builder must have closed the cavity at the top,
Why was he surprised the top of the cavity was not pumped?

Ginger83

Calahonda52 wrote: »

the top 9", pressure, ****ox

Yes that is what they said when they inspected.

Ginger83

chooseusername wrote: »

I'd say they didn't fancy pumping beads into a 9" high cavity not knowing the make up of the cavity.
Op says there is bridging but not what type.
Joists may be crossing the cavity
Also, if pumped insulation stopped at the top of inner leaf,
it means the builder must have closed the cavity at the top,
Why was he surprised the top of the cavity was not pumped?

The bridging is 9×2.
The cavity is not closed as we made holes in the ceiling and bridging to try and find out what is wrong and you can reach in and grab the beads. We held a candle above the ceiling as a test and it blew out.

the_pen_turner

are you saying there is wind through the ceiling joists. that definetly shouldnt be like that

Ginger83

the_pen_turner wrote: »

are you saying there is wind through the ceiling joists. that definetly shouldnt be like that

Yes and holes were drilled in the walls to measure the cavity and there is strong wind coming through holes

chooseusername

Ginger83 wrote: »

The bridging is 9×2.
The cavity is not closed as we made holes in the ceiling and bridging to try and find out what is wrong and you can reach in and grab the beads. We held a candle above the ceiling as a test and it blew out.

Hats off to guts who can pump a cavity to finish at the top of the cavity
without either overflowing or underfilling, without cavity closers in place.
(unless it was pumped before the roof deck was in place.)

Ginger83

chooseusername wrote: »

Hats off to guts who can pump a cavity to finish at the top of the cavity
without either overflowing or underfilling, without cavity closers in place.
(unless it was pumped before the roof deck was in place.)

The roof was on when pumped, it's amazing how wrong they got it.
It's as if someone watched a you tube video of sticking the insulation on the deck and didn't know they had to insulate the sides

Ginger83

20201127_185532 (2).jpg

So we opened up the double plasterboard on the ceiling and made an inspection hole in the bridging at the top of the walls.
The pic shows the uninsulated space.

dathi

Ginger83 wrote: »

20201127_185532 (2).jpg

So we opened up the double plasterboard on the ceiling and made an inspection hole in the bridging at the top of the walls.
The pic shows the uninsulated space.

just to be clear in the picture is 1, the concrete block the outside leaf that rises to the parapet 2, the beads the top of cavity 3, the green 9x2 is the wall plate running the length of extension with the joists running perpendicular to the wall plate on hangers and 4, the white area in the photo with 3or 4 beads on it is the topside of plasterboard ceiling. 5, on the low side of roof how does the joists finish
6, on top of joists there is plywood and then 100m insulation plus membrane

Ginger83

dathi wrote: »

just to be clear in the picture is 1, the concrete block the outside leaf that rises to the parapet 2, the beads the top of cavity 3, the green 9x2 is the wall plate running the length of extension with the joists running perpendicular to the wall plate on hangers and 4, the white area in the photo with 3or 4 beads on it is the topside of plasterboard ceiling. 5, on the low side of roof how does the joists finish
6, on top of joists there is plywood and then 100m insulation plus membrane

1. this is the lower side
2. correct
3. this is bridging on inner leaf, joists also rest on inner leaf
4. this is the top of plasterboard that's fixed to the walls
5. joists rest on inner leaf
6. correct

the_pen_turner

take a pic back into the ceiling

is the inside of the outer leaf damp

Ginger83

the_pen_turner wrote: »

take a pic back into the ceiling

is the inside of the outer leaf damp

I will get a pic soon, sorry I'm in a wheelchair.

Yes the person that took the pic said it felt damp to touch. The white reader finish outside was stuck directly on the block. The builder claims there is a 20mm nap plaster under it but it simply is not there.

chooseusername

Ginger83 wrote: »

1. this is the lower side
2. correct
3. this is bridging on inner leaf, joists also rest on inner leaf
4. this is the top of plasterboard that's fixed to the walls
5. joists rest on inner leaf
6. correct

Is this what the make-up looks like?
edit ;
Is there a ply or osb deck missing between the insulation and the epdm?

Ginger83

chooseusername wrote: »

Is this what the make-up looks like?

Wow that's it.
The empty space is on all three sides because the bridging is in the way on the inside and opening from the outside would mean a new membrane.

No that's the exact make up