Balconey design issues

pat m

Hi
I'm currently building a storey and a half in galway on an elevated site beside the sea. just finished raft, Construction is block cavity with hollowcore. The design includes a balconey on top of the hollowcore in the corner of the upper level ie not a steel protruding balconey. Does anyone have any experiance of building and living with a balconey. I'm getting a bit nervous about waterproofing considering our climate. I still have time to pull back and replace it with large windows (with retention of course). my engineer is a bit vague to date.

any advice gratefully received.

Slig

sorry but just to clarify, is it a balcony(nothing underneath) or a terrace (room underneath)?
If its a balcony then dont project out with the same slab. There will be cold bridge and moisture ingress problems.
If its a terrace then drop the slab level, even if it means reducing the ceiling height below. the build up with insulation, screeds and waterproofing not to mention the falls needed for drainage and possibly even outlets and downpipes can be quite substantial.

There are very few people that actually get permission for balconies on rural houses so if the orientation is correct I'd go for it.

Mallini

Pat,

Waterproofing won't be an issue if the right product is installed correctly. Just make sure you step a minimum of 150mm down onto your balcony from inside. This step depends on the finish you will have on your balcony ie ... decking or paving slabs etc .... If there is a room below your balcony then get your engineer to agree an insulation detail to avoid coldbridging. To deal with the guarding fixing issue I would create a concrete upstand which would be poured with the screed on top of the hollowcore. The guarding can then be fixed on top of this (nice neat detail). This will eliminate the need to drill through the tanking and avoid the risk of leaks. Sit your engineer down and agree these details now to avoid any confusion.

topcatcbr

pat m wrote: »

Hi
I'm currently building a storey and a half in galway on an elevated site beside the sea. just finished raft, Construction is block cavity with hollowcore. The design includes a balconey on top of the hollowcore in the corner of the upper level ie not a steel protruding balconey. Does anyone have any experiance of building and living with a balconey. I'm getting a bit nervous about waterproofing considering our climate. I still have time to pull back and replace it with large windows (with retention of course). my engineer is a bit vague to date.

any advice gratefully received.

I think i know what you are doing .
You need to tank the HC slab as if it were a roof. (you probably wont have 150 required to step down as suggested previously). any junctions between outside and inside will need a lead flashing steped up 150 above FFL except at the patio door this will be sealed under door tray to lead flashing. There could be a problem with cold bridging. Warm deck roof construction on balcony with insulation under(ceiling) and all around all sides should help solve this.

Get a tech to detail this out fully before going any further.

sydthebeat

pat m wrote: »

Hi
I'm currently building a storey and a half in galway on an elevated site beside the sea. just finished raft, Construction is block cavity with hollowcore. The design includes a balconey on top of the hollowcore in the corner of the upper level ie not a steel protruding balconey. Does anyone have any experiance of building and living with a balconey. I'm getting a bit nervous about waterproofing considering our climate. I still have time to pull back and replace it with large windows (with retention of course). my engineer is a bit vague to date.

any advice gratefully received.

have you got construction drawings to work from???

i think they are a necessity when working with details such as concrete slabs, balconies etc....

Slig

sydthebeat wrote: »

have you got construction drawings to work from???

i think they are a necessity when working with details such as concrete slabs, balconies etc....

Completely agree. There are lots of standard details around but situations like this very often need a custom design done up by and Arch tech, possibly in conjunction with an engineer

pat m

Hi guys
Thanks for the input. Yes there is a habitable room underneath the balconey/terrace. The engineer thinks 8inch hollowcore for the 1st floor and 6inch hollowcore for the balconey floor area ie step down, also a raised threshold for the patio doors leading out on to the balconey. Also because their will be a wall of blocks and patio door and thus roof loadings with no wall directly underneath a large lenght of steel at least 303mm x 303mm will run under the patio door/wall both to support same and balconey floor hollowcore. I should have finalised the design sooner, however its more the issue with coldbridging and insulation i'm concerned with as i'd say the engineer will cover the structure/loading side of things and hopefully the rest too.
thanks again

pat m

What does tank the hollowcore mean?

topcatcbr

pat m wrote: »

What does tank the hollowcore mean?

Waterproof as for a watertank /swimming pool

pete6296

Hi,
I did this and its now completed, the habitable room below is 4mx2m and it all glass.
It consists of 2 120mm diameter steel beams upright with a 4m steel rsj spanning both steel uprights and these are tied with two smaller rsj's to external wall. We used timber as floor with 100mm kingspan board on top and waterproof membrane professionally installed. It was a costly job, i reckon 5k covered it, both 120mm diameter steel beams were pumped with insulation with cold bridging. All watertight so far with all the rain, we finished it with a stainless steel railing with toughened glass.
Can post a pic if anyone interested
Pete

pat m

I'm very interested, please post a picture! Was your whole floor timber joycing or just the balconey floor?

pete6296

Just the balcony floor, the rest of house was hollowcore. The reason we opted for timber is the cost of steel would double if hollowcore because of weight.

pat m wrote: »

I'm very interested, please post a picture! Was your whole floor timber joycing or just the balconey floor?

pat m

pete6296 wrote: »

Hi,
I did this and its now completed, the habitable room below is 4mx2m and it all glass.
It consists of 2 120mm diameter steel beams upright with a 4m steel rsj spanning both steel uprights and these are tied with two smaller rsj's to external wall. We used timber as floor with 100mm kingspan board on top and waterproof membrane professionally installed. It was a costly job, i reckon 5k covered it, both 120mm diameter steel beams were pumped with insulation with cold bridging. All watertight so far with all the rain, we finished it with a stainless steel railing with toughened glass.
Can post a pic if anyone interested
Pete

How did you drain away your storm water, how did you bring your water pipe through the timber floor and then through the cavity.
A picture paints a thousand words, if possible!

pete6296

With such a small area, the floor of balcony has a slight slope and for the little amount of water runs off. No water pipe at all

pat m wrote: »

How did you drain away your storm water, how did you bring your water pipe through the timber floor and then through the cavity.
A picture paints a thousand words, if possible!