Sunken Seating

[Mark68]

I have got a redundant hole in my garden from a sunken trampoline project that has now been out grown.

 

I would like to turn it into a sunken seating area with a fire pit.

 

I am think of pouring solid concrete seats the question is what do I do to keep the earth side dry.

Can i just line the hole with a damproof membrane then cut the middle out for drainage when the concrete is done.

The middle of the seating area will be gravel.

I don't want to end up with permanently damp seats. I also want the render the seats to give them a finish.

 

Any help would be great or any idea where to look.

 

Thanks

 

 

[Ferdinand]

@Mark

 

Welcome to the forum.

F

[Gone West]

Hi and welcome to the forum. I would add waterproofer and not worry too much about the concrete being wet. There are some useful videos using a shiny board in the mould to create a smooth finish.

 

[Onoff]

If it were me...I'd over complicate things!  Make a big ply board cut to the seating profile to shape the render. Rotate around a dead square central pole - use that for a parasol later if required.

 

I've mulled doing similar for a home brew hot tub.

 

 

Would need some drainage tubes down from the seat to shed standing water. A nice set of concrete steps too. 

[Ferdinand]

May be relevant whether it has ever flooded or had standing water In it, in any form.

 

Also needs to be designed to make it possible or impossible to use as a drunken-bicyclist wall of death facility.

 

Ferdinand

 

[Mark68]

Thanks Guys

 

It has never flooded

 

Does a waterproof additive really work in the concrete mix.

 

I have seen an everbuild product at £5 for 5 litres and a sika product for £50 for 5 litres

[SteamyTea]

If you make something from cast concrete, it does become almost permanent and very costly to change or dispose of.

Can't you do something with timber and rammed earth?

[Onoff]

12 minutes ago, Mark68 said:

Thanks Guys

 

It has never flooded

 

Does a waterproof additive really work in the concrete mix.

 

I have seen an everbuild product at £5 for 5 litres and a sika product for £50 for 5 litres

 

I wondered at the difference. I've been using the Everbuild Integral Waterproofer from Toolstation for years and its really good imo. 

 

Makes you wonder as Everbuild is a Sika company. Interesting to compare the dmsafety data sheets:

 

 

Then SikaProof:

 

 

[Mark68]

interesting, so would you say concrete with everbuild waterproofer becomes waterproof

 

I guess I could use a layer of DPC and add the waterproofer for what it costs.

 

Steamy tea - I know what you are saying. I am trying to go for a maintenance free option. 

[Mark68]

I guess the answer is to knock up a concrete bowl with the Waterproof additive fill it with water and see what happens!

[SteamyTea]

23 minutes ago, Mark68 said:

maintenance free option

The council has put in some recycled plastic benches nest me.

They look alright and don't wobble like the old timber ones.

[Onoff]

33 minutes ago, Mark68 said:

interesting, so would you say concrete with everbuild waterproofer becomes waterproof

 

That's the general idea!

 

I think you have to pour it it one hit. If you do a mix and let it dry then lay another mix on top, the "join" won't be waterproof.

[Onoff]

 

[Mark68]

That is exactly what I want to do just below ground and all the way round.

[Onoff]

I think you should cast steps, or a ramp to get down into it and rather than a continuous seat, break it up with arm rest/drink holders. 

 

Maybe some lions and Christians for good measure..

[Simplysimon]

11 hours ago, Onoff said:

If it were me...I'd over complicate things!

 

I've mulled doing similar for a home brew hot tub.

 

firstly a hot tub to remove rust, now a hot tub for home brew. i suppose if youre going to do it, then go big. will the next thing be the BH beer sales? BHIPA anyone?

[Onoff]

13 minutes ago, Simplysimon said:

firstly a hot tub to remove rust, now a hot tub for home brew. i suppose if youre going to do it, then go big. will the next thing be the BH beer sales? BHIPA anyone?

 

Home brew as in "DIY" not the drinky sort. 

 

Timely reminder that I've a cider kit from The Range to make sometime...luckily I've 40 500ml bottles amassed.....

[Simplysimon]

seriously?, definitely like my idea better.

[Mark68]

I'm back again with another question.

 

So my concrete seating is going to a rectangle (hollow in the middle, bit like a square polo)  400mm deep 700mm wide and 3m x 3m.

 

So that has a volume of 2.5 cu/m.

 

As it is not structural can I throw in all my old blocks and broken slabs etc as i pour to make up some of the volume? Or would it end up cracking etc 

 

Thanks

[Onoff]

Whereabouts are you? I could give you some galvanised, steel wire rope (got lots) you could wrap round and round in the formwork to keep it all together.

[Mark68]

Not a million miles away in Dorset

 

[Mark68]

Do you mean use the wire as reinforcement?

[Onoff]

1 minute ago, Mark68 said:

Do you mean use the wire as reinforcement?

 

Yes to tie everything together. Just a thought.

[Onoff]

Disappointed this isn't going to be circular and organic in it's form!

[Mark68]

I know 

 

What are your thoughts about putting the rubble in with the mix.