Constructing a raised deck / balcony - advice please

[completehandy]

I’m planning to build a new raised deck / balcony on the back of my bungalow which is built on a sloping site. It will be around 2.4 metres out from the bungalow and probably 3.2 metres long.

The main issues are controlling costs as I’m very tight on budget, minimal on-going maintenance and ideally creating a dry area underneath to store the mower and other gardening tools. (It will be around 1.7 metres off the ground)

At the moment my plan is to create the main decking structure from timber supported at the front on brick columns and by a wall plate on the house side.

I don’t really want to use timber decking due to maintenance and the fact that it isn’t waterproof. Instead I’m considering using 18mm ply or OSB3 for the floor surface (possibly two layers) and laying a Ditra matting type product on top of this with porcelain tiles on that. I would presumably have to tape the joints in the matting and possibly add some uPVC angle or similar around the open sides to protect the edges of the ply / OSB from water ingress. Would the Ditra matting act as a waterproof layer or would I need to somehow waterproof the ply before it was laid. I know Schluter systems do some items especially for this type of application but believe they are very expensive.

What do you think? Any suggestions would be much appreciated.

John.

 

[Dan]

I wouldn't use ply outside like that.
THAT is going to be the expensive route because you'll end up redoing it using something that's actually waterproof.

What are the schluter options for this?

You may find Dural or somebody else has something slightly cheaper maybe?

Do you want porcelain tiles as the final finish? Or do you just wants use those for their durability and water resistant properties to prolong the life of the terrace?

 

[Ajax123]

As already said I think you will end up rebuilding it within 3 years. A plastic edge wont keep the water out as it will encourage capillary action which will allow water ingress at the edged. You will also have issues with expansion and contraction and possibly deflection. You could always use a concrete beam and block system or perhaps a lewis decking system or a steel tray system supported on steel joists. there have to be better systems than a bit of plywood for outdoor balcony arrangement.

 

[Dan]

Couple of old threads that might be of help. I haven't read them.

• Tiling onto OSB board
  
• I'll find a couple more in a sec I've been side tracked

 

[Dan]

I don't think it'd even do 3 years.

The first frost and you've broke the bond in the ply.

Then first wet summer you've swollen the wood, and it's expanding too.

So if you did it now, it'd last until maybe July next year. Might be Feb/March if we have one of those random sunny weeks then the random frosty weeks.

 

[Concrete guy]

You'll need planning permission if the deck is more than 30cm above ground height.

 

[Diggy]

The main issues are controlling costs as I’m very tight on budget,

doesnt seem to go with,


Instead I’m considering using 18mm ply or OSB3 for the floor surface (possibly two layers) and laying a Ditra matting type product on top of this with porcelain tiles on that.

Personally I'd be going with getting a bricky in to build me a blockwork wall and be done with it , then go from there . Without knowing exactly the situ its hard to say , but from that you'd get a more stable base imho.

Diggy

 

[completehandy]

The main issues are controlling costs as I’m very tight on budget,

doesnt seem to go with,


Instead I’m considering using 18mm ply or OSB3 for the floor surface (possibly two layers) and laying a Ditra matting type product on top of this with porcelain tiles on that.

Personally I'd be going with getting a bricky in to build me a blockwork wall and be done with it , then go from there . Without knowing exactly the situ its hard to say , but from that you'd get a more stable base imho.

Diggy

Thanks for the input so far.

Diggy, Not sure why you think ply + Ditra type mat & tiles would be particularly expensive. The cheapest option is probably softwood decking but it will need ongoing maintenance and can be very slipery when wet.

I've now spoken to Schuter Systems and they recommend using a ply base but making sure it's as rigid as possible. This would then be waterproofed with MAPELASTIC which should be run around the edges of the ply.

Onto this the Ditra matting is applied with the tiles on top.

I'll try to cost all this up to see if it's financially viable.

I realise I will definitely need planning permission and possibly building regs unless I can make it self supporting rather than tied to the house wall.

 

[Dan]

Thanks for the input so far.

Diggy, Not sure why you think ply + Ditra type mat & tiles would be particularly expensive. The cheapest option is probably softwood decking but it will need ongoing maintenance and can be very slipery when wet.

I've now spoken to Schuter Systems and they recommend using a ply base but making sure it's as rigid as possible. This would then be waterproofed with MAPELASTIC which should be run around the edges of the ply.

Onto this the Ditra matting is applied with the tiles on top.

I'll try to cost all this up to see if it's financially viable.

I realise I will definitely need planning permission and possibly building regs unless I can make it self supporting rather than tied to the house wall.

Try costing also with BAL Fastflex Single Part, without the ditra. One less adhesive layer and no uncoupler required then and it doesn't matter too much if there's micro-movements under it. Fastflex won't let it through like cement-based would.

 

[Old Mod]

A better option IMO would be the use of Ditra Drain instead of Ditra matting. If u have any water penetrate ur tiling it will run into the Ditra Drain and run away to the front of your decking.
Using Schluter profiles at the front edge it will drain straight into your guttering, whether it be regular guttering or Schluters own guttering.
Ditra Drain comes in two profiles, 4 & 8mm deep.
Obviously first tanking with the Mapelastic and Mapei Banding to seal the edges. The Ditra Drain has joining flaps (for want of a better description right now haha) for joining the matting along its joints.

 

[Diggy]

Jeepers , you guys seem to be over complicating matters imho. Blockwork , concrete sub , tiles , solid as a rock.
I stand by my earlier post that all the ditra / ply / brick pillars would be more expensive , its roughly 8m² so thats 80 quid in ditra or fastflex for starters.

Anyway not trying to get into an arguement :0) .

Imho ply outside , in the sun is mucho likely to warp and Ditra or Fastflex wouldnt cover you for that.

All imho of course.

Diggy

 

[Dan]

Totally makes sense.

 

[Old Mod]

Anyway not trying to get into an arguement :0) .

Don't do arguments on here anymore!

 

[Ajax123]

Jeepers , you guys seem to be over complicating matters imho. Blockwork , concrete sub , tiles , solid as a rock.
I stand by my earlier post that all the ditra / ply / brick pillars would be more expensive , its roughly 8m² so thats 80 quid in ditra or fastflex for starters.

Anyway not trying to get into an arguement :0) .

Imho ply outside , in the sun is mucho likely to warp and Ditra or Fastflex wouldnt cover you for that.

All imho of course.

Diggy

Yup. Proper outdoor construction. Beam and block maybe 20quid a square meter.

 

[completehandy]

Yup. Proper outdoor construction. Beam and block maybe 20quid a square meter.

I did think about block & beam but remembering there will be no supporting walls, only two columns plus the existing house wall I can't really see how they could be supported. In addition I need to be able to build this myself which is why the relatively light weight of timber beams, ply etc. was my preferred solution.

Ditra Drain was actually the recommended solution rather than Ditra Matting but I was a little concerned over costs. I was hoping to use a Ditra type mat rather than actual Dirta to help keep the costs down.

On Monday I'll have a word with both BAL & Mappi to see what they think about using either Fastflex or Mapelastic.

John.

 

[WetSaw]

If you want to keep costs down then block and beam will do that. A few pillars to support the main beams ( 2 ×1.6m are easy to move) then the other beams on top. 2.4m are a bit lumpy on your own ( I'm not a big guy but can move 3m by myself with the right techniques!) but far from impossible

 

[Ajax123]

So let me get this straight. You are looking at a wall plate on the house wall presumably the full length if the deck, and the a column at either front corner. Is that right. I.e no supporting frame?? Or am I reading it wrong. No frame will make it a bit trampolinish.... I'm sure you've thought of that and I am just reading it wrong....

 

[completehandy]

So let me get this straight. You are looking at a wall plate on the house wall presumably the full length if the deck, and the a column at either front corner. Is that right. I.e no supporting frame?? Or am I reading it wrong. No frame will make it a bit trampolinish.... I'm sure you've thought of that and I am just reading it wrong....

Alan,

Essentially you're correct in that there would be a wall plate and two pillars to support the corners.

Between the pillars would be a front beam of something like two pieces of 245 x 44 bolted together. From the wall plate out to this beam would be 170 x 45 joists at 400 centres on top of which goes the flooring. This is all based on a Timber Decking Association code of practice the main variation being that their designs are intended to support timber decking whereas I really wanted to avoid this. If I can't come up with anything else I may look at composite decking which would resolve the ongoing maintenance issues but would not give me the dry storage area below and would probably be more expensive than ply and tiles.

 

[Ajax123]

Alan,

Essentially you're correct in that there would be a wall plate and two pillars to support the corners.

Between the pillars would be a front beam of something like two pieces of 245 x 44 bolted together. From the wall plate out to this beam would be 170 x 45 joists at 400 centres on top of which goes the flooring. This is all based on a Timber Decking Association code of practice the main variation being that their designs are intended to support timber decking whereas I really wanted to avoid this. If I can't come up with anything else I may look at composite decking which would resolve the ongoing maintenance issues but would not give me the dry storage area below and would probably be more expensive than ply and tiles.

Phew.... I still think though that there will be too much movement for tiles. Good luck with it though.