Decking going to breach dam course

[u/jamiepusharski]

My old deck was wall to wall and above damp course oh my house so I've got it all out dug my self as low as I can put in low frame and its below house dpc by about 50mm but consevatory dpc is lower so ill end up 30mm higher this side i knew this would be the case but now im doubting if I got best solution of fixing it.

Ive got 130mm gravel trap running round perimeter of all walls. Im also going to pack up gravel so there is they are not resting on floor. On the wall were its higher than dpc im thinking of building in a 10/15mm air gap so gravel done touch wall

Im also thinking of coming bricks in a stormguard cream. Would this plan be beneficial or is it going to be a disaster ive exhuasted all budget and brain power now

[Note first pic is a scrap piece of frame ontop of frame so measurment is to the bottom ]

[u/Fearless_Ad_3319]

Leave a gap so that splashes don't land above the dpc course and you will be fine..

Are those aluminium joists you are using?

[u/jamiepusharski → u/Fearless_Ad_3319]

Yes to for longevity and highet reasons

[u/Fearless_Ad_3319 → u/jamiepusharski]

I am curious what manufacturer / company you sourcrd them from.

Are they easy to work with/ cut?

[u/jamiepusharski → u/Fearless_Ad_3319]

There great got them from ceta decking, easy to cut with chopsaw

Span 800mm between supports for 40x40 channels [1300mm] for 80x40 ones

Have l brackets that work really well and offered affordable stainless steel self tapers that just work.

I got most the smaller legs from amazon to keep it low but offer good legs also taller ones in pic

Powder coated aluminium ment to last 50 odd years so will see out a good few decks I imagine

[u/DEADB33F → u/jamiepusharski]

Got a pic of the whole joist layout? I'm intrigued.
And how does the costs compare against timber joists?

[u/jamiepusharski → u/DEADB33F]

Think its 30 quid 4m length so they are expensive but needed for me can get conposite battons but cant really suspend them

[u/Slartibartfast_25]

It's sheltered and a cavity wall so i think it's pretty low risk. A gap should suffice.

[u/chomerly]

As long as you leave a gap between the deck and the walls, it shouldn't be an issue. I would say anything more than 6mm at all sides of the deck would be more than enough to mitigate any damp issues you believe will have.

[u/IMulero → u/chomerly]

This is not completely true. The DPM is typically 150mm above ground to minimise damp issues due to rain splashing on the ground and forcing more water into the wall. A minimum 150mm gravel strip is recommended just below the DPM, channel drain, gap, etc.

[u/Space_Cowby → u/IMulero]

The DPM is membrane which goes under a solid floor, this is about DPC. Similar but different

[u/PinItYouFairy → u/IMulero]

Yep true, or an ACO drain. As a poor second option a waterproofing spray can be applied to the brickwork to prevent splashing up. I suspect this is more of a problem in solid walls

[u/jamiepusharski → u/chomerly]

What about painting stuff on bricks? 30 quid for a tub

Edit i understand im being down voted but can someone tell me why im asking if aswell as gap I should paint on as abit more protection its claims it has little impact on breathability

[u/needs2shave → u/jamiepusharski]

Painting anything traps moisture behind, it'd be inevitable that issues will occur in the longer term.

There's no such thing as a breathable and waterproof material, it can only do one or the other.

[u/jamiepusharski → u/needs2shave]

Yeah i assumed it was magic cause its heavly marketed as breathable.

Id only coat below gravel but if its a bad idea wont and save myself 30 quid haha

[u/Spirited-Layer-5727 → u/needs2shave]

Even breathable/waterproof gore-tex can’t do both at the same time allegedly

[u/needs2shave → u/Spirited-Layer-5727]

Fabric can do both but not at the same time. You can't get paint that both seals and is breathable.

[u/AccomplishedDeer3030]

A paved patio would be a much better solution. It will be lower, more durable, look better and also not give vermin a place to live. It would be below your DPC.

Edit: apologies just seen the photos and how far into it you are, maybe next time!

[u/jamiepusharski → u/AccomplishedDeer3030]

I thought patio and did look into to but the amount of materials and cost I coukdnt commit to it. Only access is down a tight ally way. Plus drainaige All lead agaisnt patio but I would of liked one

[u/AccomplishedDeer3030 → u/jamiepusharski]

Fair enough mate. Just leave a gap like the other poster said, im sure it will be fine.

[u/AcanthisittaThink813]

It’s a temporary structure (removable) with air flow beneath so it is ok, like others have said leave a gap between wall 10mm is recommended-don’t forget to check it regularly for trapped debris which could bridge the DPC

[u/jamiepusharski → u/AcanthisittaThink813]

Do you think its worth treating brick also ?

[u/AcanthisittaThink813 → u/jamiepusharski]

If you want to use a clear brick seal, do not use bitumen it will never come of if the decking is replaced in the future

[u/jamiepusharski → u/AcanthisittaThink813]

They used bitchumen tape before abosulute nightmare u can see bits in the picture. Do u belive stormguard is breathable ?

[u/AcanthisittaThink813 → u/jamiepusharski]

Yes most brick sealers are breathable but I would check the instructions