Urgent advice needed - Block paving foundations

[pieinthesky]

We are having a patio built from blocks with a surrounding wall approx 18 inches high cut into the lawn. The patio will slope away from the house to the wall.

I am (unfortunately) a bit suspicious of contractors and now they have started work am unsure if they are puttting in the correct foundations.

Please can anyone tell me the minimum depths and materials required for the patio and the wall.

Also if the patio slopes to the wall will any drainage be required at that point.

I will ask them what they are planning but would like to be armed with a bit of knowledge beforehand.

Any advice would be much appreciated.

Thankyou

Angela

[GB_Groundworks]

the main site has a wealth of really useful information taken from it is this image.



but make this your 1st point of call

block paving


from what you say, i assume the wall will be retaining the lawn so the wall will need a strip footing of concrete pouring.

now depending on what material the wall is being faced with will determine the footing,

personally id use 5 newton blocks laid flat with tie wires to hold the face so assuming a face thickness of 100mm i'd go with a 500mmx150mm concrete footing. now this is probably overkill but not looking at the job its hard to say, can you post pictures?

then again depending on what the ground conditions are like 100-150mm of type 1 mot properly compacted, i'd lay it on some geotextile as well finishing level with top of the concrete. (this is a good way to tell what teh contractors are like, as if they are using old bricks and flags etc that hasn't been crushed or screened)



i''d also want to put some form of linear drain in along the base of the wall if it is being drained that way, think travis's do a plastic 5 ton channel drain for about 12 a metre. and then that connected into an appropriate outfall/surface drain.

[pieinthesky]

Hi GB Thanks for the post.

I have just got back in (they have been working today) and my suspicions, unfortunately have been correct.

They now have the sub-base down, which is compacted type 1 hardcore I believe. I measured it in a couple of places and found it to be 1 to 2 inches deep. Also they have laid it over some of the existing slabs. The level with sand and blocks still to go is 4 to 5 inches below the damp proof course.

The cement base for the wall is 1 to 1.5 inches deep and is laid on top of the sub base. The wall is to be 2 bricks deep (I assume - no breeze blocks around) and up to 18 inches high, the lawn will be to the top behind the wall.

I have looked at the info on this excellent site (thankyou) and it seems to me that their work is a bit poor.

Am I justified in getting them to do it properly or to throw them off the job.

I would appreciate some expert advice.

[seanandruby]

I would with out a doubt kick them off the job. there is no excuse for skimping on materials, or poor workmanship.

[pieinthesky]

Hi Sean

Thanks for your post.

Am I right in concluding that

A The Sub Base is insufficient
B The Wall footings are insufficient
C The final patio level will be too close to the house damp proof membrane

I am new to all this so would appreciate your opinion in a Yes/No format

Also is it acceptable to put sub base over existing paving slabs if they were solid?

I want to ring them tonight if I have to stop them working and am very apprehensive about doing so. I need to be sure I am right.

Thanks

Angela

[James.Q]

yes
yes
yes

[msh paving]

sounds like a very poor standard,best to let them go b4 they take money from you,

[seanandruby]

Hi Sean

Thanks for your post.

Am I right in concluding that

A The Sub Base is insufficient
B The Wall footings are insufficient
C The final patio level will be too close to the house damp proof membrane

I am new to all this so would appreciate your opinion in a Yes/No format

Also is it acceptable to put sub base over existing paving slabs if they were solid?

I want to ring them tonight if I have to stop them working and am very apprehensive about doing so. I need to be sure I am right.

Thanks

Angela

25/50ml sub base is not sufficient if you are using one.
concrete foundations 25/40ml inadequate.
should be 150 below damp, maybe could get away with slightly
higher, only slightly.
some sub base over existing slabs wont do,needs to be
consistent. try to use metric if you can as i have converted
for you. good luck.

[pieinthesky]

Thankyou all for your assistance.

I will call them and give them the bullet.

I am very glad I didnt pay them a deposit but its unfortunate that I have a drive full of bricks!

Thanks again for helping me spot it now, not in a years time

regards

Angela

[seanandruby]

your welcome. it would'nt of taken a year to spot things going wrong.

[pieinthesky]

I have instructed them to stop work and remove their tools and materials.

They werent too pleased !!!!

They offered to dig it all out and start again but the trust has gone and I havent time to watch over them.

I only hope they tidy up and there are no repercussions.

Is there anyone on this forum who wants to come and give me a quote? I am near Milton Keynes

Thanks

[GB_Groundworks]

the fact that you had worries or suspicions in the first place kinda shows they weren't upto scratch.

how did you find them?

always try and get recommendations and at least three quotes and ask for a specification, if they wont provide a detailed spec then they aren't worth using.

hope you get it sorted

Giles

[dig dug dan]

HI

I am in hemel.Not a million miles away. I would be happy to quote for you?
pm me if you like

[Suggers]

I only hope they tidy up and there are no repercussions.

This is probably unlikely - a bit pie in the sky - they're not gonna be too well pleased - make sure you're at home for the denoument.
I'm sure DDD will do a proper job.

[seanandruby]

perhaps you could recommend this site to them, then hopefully they will learn to do a good job.