Ballpark figure please

[CAPTAINSAM]

Hi.

I will be building an outbuilding 25x3 (75m2) Itwill contain a gym, a computer room and maybe some guest accommodation.

Could I please have some ball park figures as to how much it would cost to both self build or build myself? I'm quite handy and can do most of the internal studding, insulating etc myself. The main thing I forsee myself needing assistance with would be foundations, walls, roof and plumbing. I could probably do this myself with some pointers in the right direction. If i bring anyone in, I would be willing to help with any of the delegated work.

PS. If there's anyone in the Essex area that can help please feel free to get in touch.

 

[Himaginn]

Just extrapolate from this, about 15m²:

Just had a quote to do this.

He told me he won't use cheap thermal blocks but use solid concrete blocks. We didn't go for insulated shed as the quote was £10k but a non insulated for £6k with rendering outside with elec socket and flat roof.

bearing in mind, you'll definitely need Building Regs approval for more than 30m². And because it'll be habitable.
You might also need Planing Permission.

 

[CAPTAINSAM]

I won't need planning but I will need building regs. I've already spoken to the relevant authorities about this.

What about materials....should I am torn between whether I should use concrete blocks as opposed to bricks. The probably won't have a cavity. Instead I plan to timber frame it internally, insulate and then plasterboard. Would this be a problem at all or will I thank myself in the long run by just building a cavity?

 

[tomfe]

If you want to do it quick do a cladded timber frame, you need 2m from your boundary for timber cladding.
No problem in doing a timber frame with a brick/block outerskin.
25m is a long wall so if you are doing it in block/brick remember expansion etc
Me likes timber cladding though

 

[CAPTAINSAM]

Sorry I might have confused some with my last post. I would prefer this not to be a timber structure but a brick/block structure (single wall). In terms of insulation, I plan to install 2x2 timber internally and fill this with insulation + plaster board.

I seek guidance as to whether the above would be a feasible and cost effective build or whether I should just build a cavity construction?

There will be maybe roughly half a meter, if that, between garden fence and building. On the opposite side there will be roughly 2 meters between fence and building.

 

[hansPulesh]

Where in Essex are you? I had a 30m2 outbuilding built in 2013, constructed of 6" single skin concrete blocks, a 6" slab of concrete with foundations dug down to 600mm. It has a flat roof with underlay and felt on it. The outbuilding has no running water in it and I did the electrics myself - cost me no more than £100 to do.

It cost me £1,000 to have it built (I didn't help at all) and it took them 5 days to do. The materials however cost approx. £7,500

If you do it yourself, please also take into consideration the parts which will be hidden - be aware that you'll need to dig trenches down to around a meter for the water pipes, electric supply, data cabling, telephone cabling, AV cabling and you'll also need to work on sewage piping if you install a shower/WC etc.

 

[CAPTAINSAM]

Hi. Located in Romford here. I have taken all you mention into account but thanks for mentioning. It's good to know I haven't missed anything out.

The main thing I am stuck on here is the building material. What type of block should I use, should I use blocks or bricks. I read everyone moaning about blocks cracking. 25M is a long wall. Will it crack if it is all blocks?

 

[hansPulesh]

Hi. Located in Romford here. I have taken all you mention into account but thanks for mentioning. It's good to know I haven't missed anything out.

The main thing I am stuck on here is the building material. What type of block should I use, should I use blocks or bricks. I read everyone moaning about blocks cracking. 25M is a long wall. Will it crack if it is all blocks?

I forgot to mention that the builders also rendered the inside and outside of the building as well.

I'm just down the road from Romford - Hornchurch.... Personally I have found that the lighter celcon blocks always crack. You also can't screw screws into them and hang too much weight off of them. For that reason I used the solid concrete blocks. They're heavier and they will cost more to install (if you're using a builder to build it for you) but in the long run they're deffo better.

Bricks will cost you a bomb. What are you considering for the look of the place in the end? If you're rendering, it doesn't matter whats below - I'd go for the cheaper option. Also, if you deffo want it to have bricks, I'd consider using the blocks on the rear and sides and bricks at the front to keep costs down and to get it finished as quick as possible.

I found Major Builders Merchants (0208 924 1122) in Ilford best on price. They came in cheaper on everything and on haggling, came down even further. If you want to use the guys I used to build the structure etc, I can pass that info to you too.

 

[CAPTAINSAM]

Is rendering necessary? I really don't care what the building looks like, aesthetically. I mean, if it becomes a problem, I could just clad it myself at a later date?

I do want solid walls that I can hang stuff off of. Could you link me to the type of blocks I would need please? I've just had a quote from a builder on Gumtree who said a 25x3 would require roughly 700 concrete blocks?

If you would pass me the details, I would appreciate that.

I am looking at getting the works started pretty soon. Hoping to start the foundation work within the next two months. I am looking at getting in some groundworkers who advertised on gumtree (will follow up references of course before awarding any jobs). How long should it take two men and a mini digger (2m max depth) to dig lay foundations and piping?

 

[hansPulesh]

If you're not too worried about the way it looks, I'd go for blocks rather than bricks. It's a big building and will need a lot of bricks. It'll take a brickie a lot longer to lay that may bricks than blocks.

I had it rendered to add a little to the strength, to make it look nicer and to keep it water tight. I also adder dye to the render so that I wouldn't need to paint it every so often.

https://www.travisperkins.co.uk/Solid-Dense-Block-140mm-10-4N/p/272786

^ an example of the blocks that I used. You can work out how many blocks you'll need - Work out the height and length of each wall and then divide that into the size of the blocks that you're thinking of using.

I'd get some recommendations for builders and make sure whoever you use comes with good reviews. I've used sites like trusted trad*r etc before but have come across some real cowboys. Ask family/friends for builders that they've used and have been happy with as well.

 

[CAPTAINSAM]

Yeah, I will definitely follow up references. I will give the number you mention a call tomorrow. See what they say in terms of price. I've just had a rough guesstimate on the phone of £150 per m3 (foundations)...that sounds quite expensive to me!

I wonder if laying foundations is hard or difficult.

 

[hansPulesh]

^^^^ Not very difficult technically, just a lot of manual labour that's all. It's a big building and so you'll need to dig a out a lot of soil/roots etc. If this isn't your daily job/like your daily job, it'll take you a fair while to do and knacker you out. Once you know where your walls are going to be, you'll need to most likely dig down 750mm into the ground by approx. 300mm.

Once done, you'll have to mix a lot of concrete and pour it into this void in the ground. If you can get it ready mixed and poured for you it will work out more expensive but will be a lot easier for yourself - you'll need to have access etc for this though. When I did mine, I asked for a 3:1 mix of shingle/sand:cement for a very strong mix to be used and it was mixed on site with a cement mixer and poured using a wheel barrow by hand as there was no access for ready mixed concrete to be poured.

That's basically all that needs to be done for foundations. But again, its a very large building and so don't under-estimate the amount of work that it'll take to get it done.

It took the guys I used 1 day to clear the back of the garden (removing 2 trees, shrubs etc) and then dig the foundations out for 30m2 by hand and so I'm guessing it'll take them maybe 2 days to do the 75m2 that you'll need. It then took them around 1/2 a day to mix and pour the concrete - so I'm guessing it'll take them 1 - 2 days to do your 75m2 (note that's once they've poured the foundations, they can't do much else till it dries).

 

[theprinceofdarkness]

Is that just for digging and removal of spoil? I don't think you have mentioned the wall height -2.4m? If you use 6" blocks then a straight wall would do, if you use 4" then you need a buttress every 6' or so. I would use medium density blocks, as said the lightweight insulation blocks seem to settle and crack (I have about 60' of newish but cracked render walls - put on to Thermalite blocks).
Foundations 56m X .6 X .6 = 19 cu.m so thats 3 skips ~@6cu. m/skip or £450 and £1k for ready mix (.3m deep). Have you got helpers for barrowing?, this is going to be a lot of work.
Frank

 

[CAPTAINSAM]

I'm happy to help with any of the labour. Also have a brother and some friends willing to help out with anything here and there. The main thing I'm trying to do is get a solid price for the foundation. I don't for a moment think this is a small job. It is a large building. The main problem I have is that I am confused.

I spoke to a builder today who said if the foundation is solid, concrete blocks (10.4n) will never crack? He suggested concrete block exterior and thermalite block internally with cavity insulation in between. What I really want to know is, will / do concrete blocks crack? I do want to be able to install wall mounted TVs, shelves etc without having to worry about any cracks.

The main objective is to use this new building as an ancillary. It might contain a guest room. However main this will be to house a gym and a cinema room as well as a computer games room. I'm hoping this building will also add value to the property.

Do prefab wooden buildings add same value as brick/mortar?

 

[noseall]

Cracking of the blocks is not a result of inadequate foundations, rather it's down to thermal movement and a poor understanding of construction methods by inexperienced builders.

A 25m long wall will require design features to counter any problems associated with ex-con issues.

A 25m x 3m slab of a structure will look horrific without any shape or design thought processes.

How do you intend roofing these 'barracks'?