shuttering-do's,don'ts or dont do its!

biffo overlord

hi folks,
I new to the forum and looking for some advice. i'm doing up and extending an old house. I'm considering building a basement under the new extension. i'd like to shutter and pour the walls, but as i'm doing this on a shoe-string budget i'd like to do the shuttering, using acrow forms, myself. Is this feasible for a self-builder to tackle on their own. My work is engineering related, plus i spent a little time on different sites around dublin during college doing summer work. Has anyone any prior experience, am I being too ambitious?
I look forward to your replies, either way.

smashey

You say your work is "engineering related". I'd still get an engineer to look at this.

ircoha

the physical work with forms is not a real problem as long as u have a bit of help. Pouring them is a lot of work

have u a design for both floor and walls based on the site conditions?
how will you address the issue of waterproofing it?.

The join between the floor and walls is the key area.

The walls will work best if u piur them in one go


As an aside consider how to insulate it also: lots of ideas on forum

be aware of the risk of it caving in between the time u dig the hole and get it poured: this risk will increase if u let the concrete trucks too near the edge, unless the excavation is well sloped back

on this last point: ensure u dont damage the existing foundations to house

Mellor

As an aside, basements aren't cheap. The same floor area at first floor is about half as costly. Basements and shoe string budgets don't fit well together.
There was another thread on basements here the other day, read over that and consider how the basement connents to the house (re fire proofing and stairs)

Cheiftan

Super idea , first a few questions?

What condition is the existing house in?
What size are the existing foundations? what type of foundation are they? concrete/stone/straw bales ( don't laugh I've seen it !!)
Are the external walls and internal walls sound and crack free?
how are you going to dig it?
Where are you gonna put the spoil?
What type of ground conditions are you going to meet ? any chance of hitting water? What kind of pumps will you use to control the water? where will you discharge the water to ?
How are you going to underpin the building whilst the dig and basement construction is ongoing? type and size of temporary works?
If it falls and I hope it does'nt ,how do you intend to get anyone unfortunate enough to be in there out?
How will you tank your slab and walls?
How many construction joints will you use and where?
Waterbar? what type?
what type , size , shape code and amount of rebar are you going to use?
What type of shuttering system are you going to use ?
How are you going to pour it ?
Is the pour going to be a controlled pour ? what is your rate of rise?
What N strength concrete are you going to use ?
What quality control measures are you going to put in place to make sure your getting the correct grade of concrete ? you gonna take cubes?
What are you going to do if your cubes fail?
What are you going to do if water starts entering your basement through the construction joints ?
When you have a good answer to all the above you might , maybe, be in a position to start.

The phrase "a little time on sites around Dublin during college " fills mw with dread , also what is an Acrow form?

"A little knowledge is a dangerous thing "as someone smarter than me once said.
Speak to a chartered engineer and a damn good builder/shuttering contractor before you venture down this road.

Mellor

I assume that you listed the above to prove a point Chieftan, as I would be surprised if you expected somebody to know the answer to alot of the questions.
Most of the questions are for a structural engineer only.
But it does highlight the complexity of a basement, and even how much more complex an extension basement is. Not easy and not cheap

ircoha

Mellor wrote: »

I assume that you listed the above to prove a point Chieftan, as I would be surprised if you expected somebody to know the answer to alot of the questions.
Most of the questions are for a structural engineer only.
But it does highlight the complexity of a basement, and even how much more complex an extension basement is. Not easy and not cheap

Mellor; Chieftan is another person: the poster here is Cheiftan, different animal/vegetable/mineral completely:D.

bradnailer

Your going to need at least 800mm space around the outer wall, your going to have to get at the wall for tanking after,I'd also keep it at leats 1000mm away from the exsiting build you'll never notice from the basement and it will save you having to under pin the founds, a reasonable size footing below the floor level of your basement floor will allow you to overlap the tanking well at the problem floor wall intersection.I go see a Engineer first even if your Architect says it's not necessary.

Cheiftan

Mellor wrote: »

I assume that you listed the above to prove a point Chieftan, as I would be surprised if you expected somebody to know the answer to alot of the questions.
Most of the questions are for a structural engineer only.
But it does highlight the complexity of a basement, and even how much more complex an extension basement is. Not easy and not cheap

Exactly Mellor, exactly, as the title of the thread says shuttering do's ,don'ts and don't do its!!

The point I was trying to make to the op was that its a massive undertaking for someone with experience who is aware of the pitfalls and unknowns let alone someone of his/her admitted limited experience.
My list of questions above , although non exhaustive will hopefully give the op an idea of the things he should be thinking of and what type of questions should be asked of a professional if he does decide to go ahead with the job

The thoughts of someone trying to do this type of work without the proper forethought and planning would as i said in my last post " fills me with dread "and as a construction professional on a information exchange based forum you have to try and point out the pitfalls to people that ask striaght forward questions.

Anyway back to the acrow form , is it some type of rough shuttering pan held together with clips ? the type farmers use for slatted tanks ? the picture posted is small and I've never heard of it , we usually use peri/doka/RMD stuff ourselves , anyone got a bigger picture?

sinnerboy

I would have added to Cheifian list

1. have you increased your personal life insurance and
2. enrolled your wife on a lone parenting course

biffo overlord

Hi folks
Sorry I haven't check in; I was away for a few days. Thank you to everyone that posted, it's good to see people so willing to share their time and knowledge.

First of all, obviously no work of this kind should be undertaken without engaging a suitably qualified structural engineer with adequate professional indemnity insurance, sorry if I gave the impression that I was undertaking the design aspect of the basement.
I don’t work in the structural/civil field. Engineers can kill people by the hundreds if they get it wrong, that goes for most engineering fields.
I have the luxury of having lots of space around the house, so yes the sides of the opening will be raked back prevent cave-ins as well as allow room to apply the outer element of the tanking system. I’m using a two part tanking system. The first part is applied to the outside of the basement; this is a bitumen type compound from AQUASEAL. The second part of the tanking in an internal cavity system from a company in England called John Newton. This is applied to the inner face of the basement and directs seepage down the wall to a gully at the junction of the wall and floor, the water is then piped to a titan sump pump and out of the basement. I suppose you could call it a belt and braces approach, but the last thing I want is an indoor swimming pool!!
Insulation is achieved by erecting an mf stud wall inside the barrier and insulated as per normal stud wall.
Damaging the existing foundations shouldn’t be an issue as I’m removing the entire back-wall, foundations and all. This leaves me 5mtrs from the front-wall.
Digging the hole and moving the spoil is not an issue, I have access to a tracked excavator and a tractor with a dump trailer. I have a dip in the field that will take care of the spoil.
Yes acrow forms are used for slurry tanks, these are what I can get my hands on. The doka system is a lovely system, but I want to be able to move the pans on my own, any of the doka I’ve seen on sites generally required a crane.
Hopefully this clears some of the confusion I helped to create.

Back to my original post, has anyone any hands-on experience, things to look out for, quick and easy tricks for manually erecting the shuttering, etc, the no. for a good chiropractor, perhaps? I realize this is an extremely long post, sorry about that!

Chieftan, you can add the black Raleigh bicycle reinforced concrete pad to you list of foundations, I’ve seen it before!!

Have a look at an ICF system, not cheap but can be erected single-handed.

It has the advantage that the "shuttering" is made of polystyrene and remains in situ afterwards and becomes the insulation of the walls.

http://www.icfinfo.org.uk/ would be a good starting point.