Dire need.Garage foundations with high water table

[SHughesNI]

I am in dire need of some help.
Quick background info. Originally from England where good builders and tradesmen are plentiful but living here in Nth Ireland there is a scarcity of decent tradespeople. Due to Covid 19 (can't get a mortgage) and the local electricity company charging me £20k+ to move electrical cables underground I am not able now to build a house so instead building a log cabin where we can live over the next few years . Planning was passed for an ICf house and we intend to build it over the next few years when the money comes in (being optomistic here). 
So far we have had 5 tradesmen (before lockdown) come to the site over the last 6 months and 1 last week come out. I have a pre fab garage ready to go once I have paid the other £5k (5K paid as deposit). Currently I cant get hold of them because they are still shut and no response to phon or emails. 
Before Christmas we hired a local groundsman to do the foundation. Instead he did everything but the foundation just piling up earth with his digger. He then charged us £1k for what he called rock but turns out it was road waste that should have gone to the recycling plant first. Having 3 young boys I don't want any potentially harmful waste on the site. 
So after that we tried again. Those that did come out to the land not one got back to us with a  quote. Only this morning after 2 weeks did one turn up and say he's off to England to do a job but if we can wait 2 months ?
Ok so what i aim to do next is post the job on a site like find a builder or if anyone can recommend a site? but what I need is a description of what needs done. I would appreciate any advice on how to build a garage in an area which will get waterlogged when the rain comes (see pic). I know I need to build high but how do I raise the foundations up? I have some rock on the land which I can dig out as I have done already. I have attached images of the finished garage along with the foundation drawings by the garage company. 

Any help / advice would be greatly appreciated.
 

Edited June 1, 2020 by SHughesNI
To add photos of my setup

[Declan52]

You just need to build it up with block to get you to whatever height you need. You will end up with a blockwall with a large hole in the middle into which you will backfill and then pour concrete to form your base.

Road waste is often used as it's much cheaper than hardcore.

With most building yards only opening in this past week or two nearly all the trades have been sitting at home not earning so they will pick the job that will keep the rust of the pan for the longest, that's why your guy has went to England.

Your going to have to put some land drains in to divert any water from the area to a ditch/drain or it will always be wet.

Where in NI are you.

[ToughButterCup]

6 minutes ago, SHughesNI said:

I am in dire need of some help... I need (is) a description of what needs done. ...

 

• Make a plan of the area
• Do a soil profile
• Look at the local land drainage with care.
• Look at similar buildings in the neighbourhood: what can you learn from a simple look-see?
• Design the garage
• Give those  documents to (a) builder(s)
• Agree a price.
• Sit back, relax

There are a few ways of doing those things: professionals will prepare documents so that your risks are lower, or you could do all that prepapratory work yourself. It depends on your appetites for risk and cost .

 

If you don't write it down and present it simply, it opens up all sorts of opportunity for mis-communcation

[SHughesNI]

Hi anonymousbosch. Unfortunately the last time i gave these documents to a builder I was screwed over. They did work except what i had asked them to do and charged me £1k for the privelege of road waste.  
Regarding your points:
 

• Make a plan of the area - plan has been made and approved by planning.
• Do a soil profile. Soil profile is clay with small content of sand. Foundations need to be deep also due to trees nearby. 
• Look at the local land drainage with care. There is a hill behind the garage and trees. A french drain is ready to be put in. This is why the garage needs to be raised also. My question is how do you raise the garage. 
• Look at similar buildings in the neighbourhood: what can you learn from a simple look-see? - none at this low level. None pre fab either.
• Design the garage - garage designed already see pics.
• Give those  documents to (a) builder(s) - Work has been piling up for builders and it looks like i will have to underake the work myself hence the requested advice. 
• Agree a price. see above
• Sit back, relax - see above

Edited June 1, 2020 by SHughesNI
add photos to explain

[Russell griffiths]

Ok, you need to do some homework 

the reason is you need to sound like you know what your talking about, otherwise you will come across as a numpty and somebody will take you to the cleaners. 

Do this. 

Work out which way around you want the building 

look at the large door location and work out roughly where this will sit on the site

bang 2 pegs in the ground to mark door

bang 4 other pegs in the ground to mark 4 corners of building. Rough not accurate 

look at the height of the pegs at the door, draw a line on these at your ideal finished floor height. FFH. 

Tigh a bit of string to these pegs on the mark and walk to the lowest corner, lift string until it looks level ish, get somebody to look at string while you hold it up. 

 

Ok now you will have an idea how much fall you have from ffl at the door to the lowest bit, measure this and do a sketch, look at mine and fill in the blanks. 

Come back on here and tell us then we can come up with a cunning plan. 

[ProDave]

The key thing with ground like that is get the foundations in now, while the ground is dry.  If the water table then comes up in winter it won't matter.

 

This garage foundations is basic stuff for a builder.  Perhaps mention when talking to contractors about the garage that you will be building the cabin and eventually a house so you hope to find a reliable builder that you can work with and they might be more willing to be agreeable.

 

Post any quotes you get here before you accept them.

[ToughButterCup]

54 minutes ago, Russell griffiths said:

Ok, you need to do some homework 

....

Come back on here and tell us then we can come up with a cunning plan. 

 

You just might find too much advice on BH, but you won't feel anything like as 'exposed' after submitting your plans to the Commentariat  sometimes called Hive  here.

 

I have a strong feeling ( zero evidence - just a feel) you need to network: find out who's good, whose bad, who's indifferent and who to stay the Hell away from.

Network, with the emphasis on work :  Its hard work.

[joe90]

1 hour ago, SHughesNI said:

charged me £1k for the privelege of road waste.  

I presume you mean scalpings, they grind the old surface of tarmac off to make way fir new tarmac. I bought loads of this from a contractor working in our area and it’s been great, compacted very well for paths and our drive, never heard about recycling it apart from storing to be sold on.

[dpmiller]

Looks more like uncrushed stuff as-dugout..

 

As Declan said, tell us where you are. There certainly isn't any shortage of trades round these parts.

[Simplysimon]

i take it that as you know it's clay with sand, you know how deep to put the hardcore in to? the pile of recycled material will be fine for bottoming, compacted well with type 1 on top. as @Declan52 says, you can build up in block and fill with concrete, alternatively you can build up in well compacted type 1 and then shutter the slab on top.

[Temp]

How practical are you? It only took me an hour to learn how to abuse a mini digger.

 

I'm thinking something like.... 

 

1) Prepare an area about 0.5 to 1m bigger all around.

2) Excavate out say 250mm

3) Use Wacker plate to compact the ground.

4) Spread out the rough hardcore you have. Perhaps omitting any massive lumps or breaking them first.

5) Compact it.

6) Add clean hardcore.

7) Compact it again.

? Spread 25mm sand blind to prevent punctures to membrane in 11). Compact again.

9) Construct shuttering from 175mm wide boards on edge. Drawings say 150mm minimum thickness of concrete even below steps in sections B-B and C-C. I would use enough hardcore in step 6 to  arrange for the top edge of the shuttering/concrete to be say 100mm above surrounding ground level. Hammer in rebar pegs to stop the wet concrete bending/pushing out the shuttering.

10) Double check dimensions because section A-A suggests walls must sit in right place so the drip bead hangs over the edge of the finished concrete all around.

11) Lay membrane to stop water in concrete draining out before it sets.

 

I'm not 100% sure how best to form the notches/steps shown in sections B-B and C-C. Perhaps prepare blocks of wood to be pressed/vibrated into the wet concrete and fixed to the shuttering while it sets?  Plan ahead for how this will be done! Thin boards may warp when wetted by the concrete? Sheets of WBP or wrap timber in plastic might work?

 

12) Calculate volume of concrete required and add a bit just in case. Order concrete with reinforcing fibres.

13) If readymix lorry won't be able to reverse right up to the shuttering consider hiring a dumper for transporting the concrete across site.

14) bribe at least four friends to be there to help spread out and level the concrete using spades, rakes and long boards across the top of the shuttering. Important it's level in step 9.

15) Crack open beer.

 

If ground really wet dig French drains around outside?

 

Edited June 1, 2020 by Temp

[Temp]

PS Those steps in B-B and C-C are to stop water being blown in.

PPS If you arrange for the top of the slab to be 100mm above ground level you may need small ramp at main entrance. 

[joe90]

11 hours ago, Temp said:

If ground really wet dig French drains around outside?

I agree, I am on very high water table and solid clay (resembles the Somme in winter), we backfilled the foundation trenches after the blockwork was at DPC with graded drainage stone and a trench to a nearby ditch and it’s worked very well. We did the same with the house. Builder also placed same stone 1 meter wide around build to work from and it saved soo much mess during winter. If you backfill foundation trench like I did it saves having to dig a French drain ?

[SHughesNI]

On 01/06/2020 at 16:04, joe90 said:

I presume you mean scalpings, they grind the old surface of tarmac off to make way fir new tarmac. I bought loads of this from a contractor working in our area and it’s been great, compacted very well for paths and our drive, never heard about recycling it apart from storing to be sold on.

I wouldn't call it scalpings. It should have gone to the recycling centre. This stuff was from a road way back and has possible contaminants https://adeptus.co.uk/waste-management/reuse-road-planings-containing-coal-tar-pahs-permit/ Not something I even want to think of leaching into the soil as I want to grow veggies the lot

 

[SHughesNI]

On 01/06/2020 at 16:58, dpmiller said:

Looks more like uncrushed stuff as-dugout..

 

As Declan said, tell us where you are. There certainly isn't any shortage of trades round these parts.

Based in Crossgar.

[SHughesNI]

Thanks for all the advice so far. It is giving me a clearer picture of what I need to post on a job quote website. the problem is of course with Covid all the best builders are backlogged for months ahead. there is a little part of me that says 'go on do it yourself' but I don't have the money to balls it up and do it again. 

Going to have a look at the suggestions and as someone said maybe come up with a cunning plan

 

[SHughesNI]

22 hours ago, Temp said:

How practical are you? It only took me an hour to learn how to abuse a mini digger.

 

I'm thinking something like.... 

 

1) Prepare an area about 0.5 to 1m bigger all around.

2) Excavate out say 250mm

3) Use Wacker plate to compact the ground.

4) Spread out the rough hardcore you have. Perhaps omitting any massive lumps or breaking them first.

5) Compact it.

6) Add clean hardcore.

7) Compact it again.

? Spread 25mm sand blind to prevent punctures to membrane in 11). Compact again.

9) Construct shuttering from 175mm wide boards on edge. Drawings say 150mm minimum thickness of concrete even below steps in sections B-B and C-C. I would use enough hardcore in step 6 to  arrange for the top edge of the shuttering/concrete to be say 100mm above surrounding ground level. Hammer in rebar pegs to stop the wet concrete bending/pushing out the shuttering.

10) Double check dimensions because section A-A suggests walls must sit in right place so the drip bead hangs over the edge of the finished concrete all around.

11) Lay membrane to stop water in concrete draining out before it sets.

 

I'm not 100% sure how best to form the notches/steps shown in sections B-B and C-C. Perhaps prepare blocks of wood to be pressed/vibrated into the wet concrete and fixed to the shuttering while it sets?  Plan ahead for how this will be done! Thin boards may warp when wetted by the concrete? Sheets of WBP or wrap timber in plastic might work?

 

12) Calculate volume of concrete required and add a bit just in case. Order concrete with reinforcing fibres.

13) If readymix lorry won't be able to reverse right up to the shuttering consider hiring a dumper for transporting the concrete across site.

14) bribe at least four friends to be there to help spread out and level the concrete using spades, rakes and long boards across the top of the shuttering. Important it's level in step 9.

15) Crack open beer.

 

If ground really wet dig French drains around outside?

 

Thats a lot to take in and will study it in depth. Many thanks for taking the time and effort to give me some advice.

[dpmiller]

1 hour ago, SHughesNI said:

Based in Crossgar.

The chap that did my groundworks - a trusted friend I'd add- happens to be a baseworks contractor for H2, I could ask him if he fancies Crossgar for a run...

[SHughesNI]

11 minutes ago, dpmiller said:

The chap that did my groundworks - a trusted friend I'd add- happens to be a baseworks contractor for H2, I could ask him if he fancies Crossgar for a run...

you could indeed. I imagine he would be very busy but on the off chance he fancies working solo with social distancing being observed I'd appreciate you giving him a shout

 

[Temp]

2 hours ago, SHughesNI said:

Thats a lot to take in and will study it in depth. Many thanks for taking the time and effort to give me some advice.

 

It's based on what I did for a 6m*6m slab. The hardest part was levelling the concrete. The delivery driver took one look at me and the wife and recommend adding a bit more water to make it easier for us before unloading the first bit into my rented dumper. It was physically hard work raking it into corners and then rubbing a beam back and forth across the top of the shuttering while trying to scrape it flat. 

 

 

[SHughesNI]

On 01/06/2020 at 15:31, AnonymousBosch said:

 

You just might find too much advice on BH, but you won't feel anything like as 'exposed' after submitting your plans to the Commentariat  sometimes called Hive  here.

 

I have a strong feeling ( zero evidence - just a feel) you need to network: find out who's good, whose bad, who's indifferent and who to stay the Hell away from.

Network, with the emphasis on work :  Its hard work.

I will take as much advice as people can give    Not sure what you meant by submitting plans? Do you mean to someone on here called Hive?

 

[SHughesNI]

On 01/06/2020 at 20:17, Simplysimon said:

i take it that as you know it's clay with sand, you know how deep to put the hardcore in to? the pile of recycled material will be fine for bottoming, compacted well with type 1 on top. as @Declan52 says, you can build up in block and fill with concrete, alternatively you can build up in well compacted type 1 and then shutter the slab on top.

Unfortunately the material wasn't recycled. It should have been and I was told it was when I handed over the £1k but since found out that it was to be taken to the recycling centre so the stuff needs to go. I have some rock that can be dug up and used instead.. Thanks for message

[SHughesNI]

On 01/06/2020 at 21:58, Temp said:

PS Those steps in B-B and C-C are to stop water being blown in.

PPS If you arrange for the top of the slab to be 100mm above ground level you may need small ramp at main entrance. 

You know I am not sure if this is even replying to you. I can only see the quote button. 

Everything you have said is what I have seen online and other sites so this is the way to go. The most important part is the raising as high as possible using the hardcore which I have. Great idea about wrapping the wood and using for the steps. Haven't been able to find any info on that so good advice
 

[joe90]

@SHughesNI I didn’t know about coal tar till you posted above, why not ask your builder to prove it’s not coal tar, /ask for your money back/ask him to remove it/talk to trading standards?

[SHughesNI]

1 hour ago, joe90 said:

@SHughesNI I didn’t know about coal tar till you posted above, why not ask your builder to prove it’s not coal tar, /ask for your money back/ask him to remove it/talk to trading standards?

Oh I did all that and even gave him the opportunity to remove it as I owed him some money for some work done. He didn;t deny it was potentially harmful and said there was more waste in there than he had thought his mate was bringing down. As I owed him about £800 for work done I am not too much out of pocket but yes that stuff can be harmful especially in roads built before 1980s .. Thank goodness for the internet ☺️