Please Help - Building Extension

[ziggy1979]

hi All

Just had a builder round today for a quote for a two-storey extension (one room on each floor approx 3m x 3m). I would be extremely grateful if you could help with the following questions:

1. Builder said the "footings" (foundations?) would need to be at least 1m deep but in some cases could be up to 2m. This seems like a lot so I was wondering whether this could be because its a 2-storey extension - property is in London and I think the area is predominantly clay.

2. Builder said that cement lorries could be expensive and suggested that two laboureres could mix the cement for the footings in a couple of days with a small cement mixer. Is this feasible or is it a false economy?

3. Builder said that only a certain number of levels of brick could be laid in a day (about 6 bricks high). Is this correct or is he just trying to make the job longer than it should take? If this is the case, is there any way, for example, by using a quicker drying cement mix, that more could be done in a day?

4. A manhole would need to be moved. Can this be expensive and does the Council need to be involved? He said that this would not be quoted for until the ground was dug up, etc. etc. Any tips on getting this ok'd by the Council without it taking a long time?

Thank you all so much for all your help!

 

[^woody^]

Get another builder to quote - one that knows what he is talking about

 

[Vee239]

We're having the same thing done at the moment but also with a rear single storey.

1. We had to go 2.1m deep for footings in the corner nearest trees, stepped to 1.8 and then 1.5m. The council will look to cover themselves - ours is Brent.

2. Concrete was delivered and poured in during the course of a morning. Mixing on site is a false economy imo but then I'm not a builder.

3. Our walls were done in grey blocks (don't know the techy term), and yes, they did lay about 6 course at a time, waiting for them to dry in between.

4. Its not the council you need to worry about, its Thames Water.
They need to be satisfied with wat you're doing. Give them a call yourself to see what they say about your particular case.

ps, where in London are you ?

 

[chessspy]

Hi, Ziggy.
For goodness sake have nothing to do with whoever it was said such drivel.
It is possible that the foundation dig might go deeper that 1m but that is sorted onsite at the time, if you ask a neigbour locally if anything like that happened you will know what to expect.
There are rules about how high one can build in a day without support, but these rules are not likely to be applied very strictly, and in any event even if the DS insisted on not going more than 3ft high that is inside and out, so plenty for a days work.
It is very cost and labour effective to get a readymix pour for foundation concrete, and the DS will like it as the mix is controlled and accurate.
Please get a recomendation from someone locally who had something similar done and was satisfied.
Get 2 or three quotes from local builders.
Don't pay money up front, anyone who can't afford to do the job will be no good.
It is just about ok to order the materials and pay for them yourself, but see all bills and check local prices.

 

[willroy]

Firstly footings minimum depth is 1m depending on trees etc.I have an oak tree at the bottom of my garden approx 13meters away so had to go to 2meters nearest tree stepping up to 1.5 furtherest away.Concrete footing is most economical and quickest get a few quotes from local suppliers first will give you an idea each load is 6-7 m/cubed .Once footings dry a few days, building can commence up to dampcoarse level then you put the floor slab in.Once dampcoarse level is done you extension will be up in no time .Built mine from dampcoarse to wall plate in nine days (breeze block off coarse).For a 3x3 meter extension should be reasonably cheap around £1000-£1500 per square meter .I built a 8x4meter costing me around ££30000 but i did work for the builder labouring etc

 

[noseall]

footings are generally a minimum of 1m deep. ground conditions can sometimes render trench footings too deep to be viable! in this instance piled foundations or an engineered raft are necessary.

readymix is financially the most suitable provided in can be shot straight into the trench. when it has to be moved great distances then things get tricky. readymix plus a concrete pump is the next best thing. otherwise moving a 6 cubic metres of concrete before it sets is an utter nightmare.

engineering bricks can be problematic in the winter particularly a wet winter. also, dense 7n blocks can be stubborn if you need to muck up. but on a decent sized project the brickies can usually move to a different part of the build and return to previous work and carry on.
you will have few problems in the summer.

any work below ground is guesswork. no one is clairvoyant and non of us has x-ray vision. if the drains are less than 750mm deep then there should be no problems.
very deep drains = very expensive job. and building control should be notified.

 

[ziggy1979]

Guys ... thanks ever so much for your help ... it is really really useful!!!

BTW Vee239 we are in Brent too ... did you find the COuncil difficult or were they easy and helpful to work with?

Noseall, how would you get cement to the back of the house (there is only a narrow side access) ... can a pipe be run through the garage and out the garage window or is def not possible? If it can be done, is there a limit to how long the pipe can be?

 

[willroy]

I built a sort of log flume out of scaffolding planks lined with visquine .Set up 3 starting high at mixer end then going lower around a bend.Worked a treat so long as the concrete is nice and wet.

 

[Vee239]

BTW Vee239 we are in Brent too ... did you find the COuncil difficult or were they easy and helpful to work with?

Not dealing with them personally but according to my builder the DS wants everything overcompensated and takes his time when requested to come out. Which part of Brent ? I'm in Kenton.

Noseall, how would you get cement to the back of the house (there is only a narrow side access) ... can a pipe be run through the garage and out the garage window or is def not possible? If it can be done, is there a limit to how long the pipe can be?

We had a cement mixer and seperate truck with a pump parked on the street outside the house. The mixer would empty into a device which looked like a hopper. There was load of pipework connected to this that stretched up the drive and alongside the house to the back.

 

[noseall]

Noseall, how would you get cement to the back of the house (there is only a narrow side access) ... can a pipe be run through the garage and out the garage window or is def not possible? If it can be done, is there a limit to how long the pipe can be?

a standard lorry pump can deal with a fairly long distance no problem.

front-back of a house is a doddle. they simply lay the pipes out along the floor, clip 'em together and shoot it in.

a boom mounted pump can even go over the roof of a house if needs be.

 

[westie1961]

hi,

we are planning to extend over our existing garage, one builder quoted to do this but said he would have to under pin the existing structrure.
i spoke to bc they said to expose the existing foundation then if the same as the house foundation no problem building above the garage.

If I was you -
do some research
talk to building control

get 3 quotes and use the fmb web site.
i have to admit that you will get loads of bull **** and it takes time but you will sort it

good luck