Ballpark figure please

[CAPTAINSAM]

@noseall
The roofing will be flat rubber roof.

What should I use then instead of thermalite blocks as the internal wall? My initial plan was to have a single wall made of solid dense concrete blocks which timber frame inside + insulation + insulated plaster boards. My main concern now is. I want to stop cracking. What should I use?

 

[noseall]

Timber frame will be ok for the internal skin however this will need to be built first complete with sheathing, so that the external leaf can be tied to it and will need to be designed with consideration for the weight of the roof etc.
Your builder can mitigate cracking of the external leaf by using say dense concrete blocks, expansion joints, dog-legs etc and a mortar mix suitable for movement.
Have you thought about getting it designed?

 

[hansPulesh]

@noseall
The roofing will be flat rubber roof.

What should I use then instead of thermalite blocks as the internal wall? My initial plan was to have a single wall made of solid dense concrete blocks which timber frame inside + insulation + insulated plaster boards. My main concern now is. I want to stop cracking. What should I use?

It really depends on how much you have to spend. You could do 2 skins of 4" solid concrete block with good insulation within the skins to give you more space inside. Then dot and dab plaster board on the inside and have this skimmed to give yourself an insulated outbuilding, as big as it can be. But this will obviously double your price for the blocks.

If you install 2 skins and then a timber frame as well, your walls will be near enough 18" thick - you're loosing a lot of internal space.

Any blocks that you use will crack if not installed correctly. The problem with your building is that without checking soil, trees etc around the area, there isn't any way of telling what would work best. Budget also plays a big part in choosing what to use. The reason that I hate the softer blocks is that they crack very easily. Also, driving any screws into them is a nightmare - As long as you don't have too much weight on any shelves, they're fine. But there is a limit to how much weight you can put on to any shelves attached to the softer blocks. There's obviously a limit to the concrete blocks too but the limit is just much higher.

You'll also need columns within your 25m walls to add some strength to it. I'd also use steel mesh in the slab that is layed to stop it cracking too.

Timber buildings have a lot of maintenance attached. They'll cost slightly less and in turn the solid built outbuilding will increase your house price more than the timber building as long as it's built well and looks nice.

 

[CAPTAINSAM]

I'm happy to spend money on the materials as long as it doesn't exceed 10-15k. Is that an adequate/generous budget?

Would it be best to just build internal and external out of the dense 10.4n blocks linked earlier in thread? I want the walls to be solid. I don't want them collapsing from the ricochet of a bag that I've kicked.

The internal framing of timber won't happen if there's a cavity wall installed. It was just one of the considerations I had in mind. However the builder I spoke to yesterday is pushing me towards thermalite blocks as the internal cavity wall and promises the wall will be solid and will not collapse and that I won't be able to punch through it...?

TLDR. Need solid walls. Which block to use.

 

[hansPulesh]

10 - 15k for for a building that size and the amount of work required is quite tight to be honest especially with 2 skins and a rubber roof (they're expensive!), electrics, plumbing, trenches. Also especially around London..... Neither thermalite/dense concrete walls will collapse by punching them. they're both quite strong in that way, its more to do with the amount of weight that you can load either type of block with.

Shelving etc being screwed into thermalite type blocks will cause you problems if too much weight is put on them. Thermalite blocks are made from mixing cement with ash - they're nowhere near as strong as solid concrete blocks which are just concrete. Thermalite blocks on the other hand have a much higher insulation factor.

I'd do my own research and see what you need the building for rather than listen to a builder that comes over to quote for you. In the nicest possible way to all builders out there, there are some who will consider what is easier for themselves. Concrete blocks weigh around 22kg (some weigh more) each whereas the thermalites weight less than half of that - which would you rather be picking up and laying all day long..... especially with such a big building!

If you're looking to hang something like a punch bag off the wall, I wouldn't touch thermalites. if however you're putting up shelves to store a load of sponges them the thermalites will work too.

It's all a balance and down to what you need. thermalites will crack if they're not installed properly. So will concrete blocks but after a lot more punishment. Take a look at google and you'll see what most people say about thermalite type blocks. They're lighter and so cheaper to lay, easy to cut/shape and more thermally efficient and that's why all the big housing companies use them for new builds otherwise they'd have to use more insulation (a further cost to them) and it'd take much longer for builds to be complete (another massive cost).

Personally, I always use the concrete blocks and would always advice them to be used.

If I were you, I'd put a proper parts list together and ring all the local builders merchants for a rough price over the phone. You have PGR Timber, Majors, Sai Builders Merchants just off the top of my head around Barking, Ilford and Harold Wood. Then ask a few builders to come over and quote for the amount of work that you want them to do for you - with and without materials, with and without foundations/electrics/plumbing etc depending on which parts you can do yourself. Oh and always try haggling too!

This way you'll get a true picture of what it will cost you and what you'll get in return.

One other thought, is the area where you're looking to build this building accessible from the road? Or will labourers have to carry the stuff through your house? - This will have cost implications too.

 

[CAPTAINSAM]

Sorry. I have been unclear (again) in my post. I meant the above budget just for walls (external, cavity and internal walls), foundations and cement. Nothing else. The site is accessible (rear dedicated access) rougly 3 meters narrowing into roughly 1.5 meters.

Thanks for all your input thus far. I think I will use solid concrete blocks for external and cavity simply because they are safer in terms of not cracking....I would use bricks but that stuff would take ages to lay.

Walls and layout - do I need to have the walls and layout all figured out before I lay foundations? One of the builders said I'd need to trench each wall???

It is looking like I have my own ground worker / landscaper. My brother is an electrician and I'm pretty much an unqualified plumber (havent sat the final exam yet). Therefore we only need someone to lay blocks. I'm just confused on what to use but it's looking like concrete blocks will be the way forward. I could probably lay it myself? I'm pretty sure I'll be able to buy some EPDM and roof it myself. Otherwise I do have a friend who does roofing.

 

[hansPulesh]

No it's fine, not unclear at all, it's just there are always so many variables with something like this that something which may initially feel insignificant turns out to change everything....

Yes you will need to trench every block wall - but internally, you can use stud partitions for which you won't need to dig a trench. And so yes you'll need to know the design of the walls etc before you can lay foundations.

If you have enough space at the back via a service road, you may find it easier and quicker to dig out the trenches with your helpers and get a truck to pour the concrete from the service road. Then wait till it's dry and have the same company to come in and lay a 6" slab with steel mesh inside it. I say 6" because it's a big slab. The norm is 4" but in a garden where you'll get big changes in temperature and roots from neighbouring trees etc, I'd air on the side of caution and go with a thicker slab.

If you do all that then you could have a builder come in and build the walls up for you.

Have you also worked out how often you'll be using the building? What months you'd be using it? How long will you be out there at a time? If its a 'summer house', will you need all the insulation/double skin during the hotter summer months? If it's a home office or a man cave - will you be out there in January when it's - 8 outside? if so then how will you be heating it? (Solar)/Electric/Gas boiler? you'll need to get a supply out there too (mostly dug into the ground).

I have a flat roof on my outbuilding, no internal walls, no insulation, single skin, a flat roof with no insulation. It catches the sun more or less all day long and by about 11am it's normally quite warm out there without any heating and in colder months too. I've bought 3 electric heaters for it but as yet not needed and so not fitted them.

I'd definitely sit down and have a proper think about what you want, how you'll use it, what will suit you best - it may save you a lot of money, make things easier for you.

If you feel you can get away with it, you could use a 6" concrete block single skin, with insulated plaster boards on the inside? There are a lot of options out there - something my uncle told me when I first did up my first house - there's no end to how much you can spend on your house - wise words!!!!!

 

[CAPTAINSAM]

The building will contain a gym, a small bike garage, computer games room, bath, shower, and maybe a guest room or two. I'd say the gym and computer room will see daily use.

I will be sticking a solid beam on the ceiling for the heavy bag. Not hanging that to any walls.

I am stuck on the logistics of the build, materials, what will and will not be sufficient / cost effective. I'm happy to spend the money but at the same time, if it's not necessary and I can achieve it for less then I would rather not spend more!

Having said that, I guess no one can make those decisions apart from me.....

Having the cement pumped in is a good idea, I did think of maybe creating some sort of piping to route it down to the site. However we have concrete and gate segregation for the far end of the garden. This building is going towards the middle where grass is. Hope that makes sense.

 

[hansPulesh]

^^^^ Lol - exactly.....

http://www.buildingmaterials.co.uk/...&network=pla&gclid=CJzM0IzvxcwCFckaGwodtRoEkw

There are so many options open to you but by the sound of it ^ this sort of thing should do the job, I'd go for the most thermally efficient plaster board and stick that to the wall internally. You'll end up with a larger internal space, warmth and at the same time at a cheaper price too.

As an example, a builder will charge you anywhere between £140 - £180/m2 - materials, while these products will cost you in the region of £7 - £10/m2 including materials.......

 

[CAPTAINSAM]

Thanks so much. Really appreciate your assistance and guidance on this.

Would I be able to drill though this and be able to fix shelves/TVs to it without a problem?

 

[tomfe]

Lol the advise on here is all over the place.
You need building regs and as such you should read up and follow them were necessary or get someone to design it or get a builder in.

Anyway
Internal skin I'd go for a light aggregate block, they arehalfway between aerated and medium block. Good for wet plastering and fixings.

 

[noseall]

Lol the advise on here is all over the place.
You need building regs and as such you should read up and follow them were necessary or get someone to design it or get a builder in

I think someone else has already mentioned getting it designed......

 

[CAPTAINSAM]

I don't really know what you guys mean when saying get it designed??? Designed by who?

I will be bringing in a brickie. But I didn't want the build to be entirely based on his opinion / what I'd easier for him. I spoke to a brickie yesterday and he quite openly told me it's hard work laying dense blocks, therefore it would be reflected in his labour, I'm quite happy to reward him monteraily, so long as he does a good job. It's just, not a lot would admit this unless promoted.

 

[noseall]

I don't really know what you guys mean when saying get it designed??? Designed by who?

Oh Lordy...!

Think - architect then work down from there.

 

[tomfe]

Designed by who?

It may be just a simple box but you still need building regs so how are you going to go about adhearing to them?
A architectural technologist might be a good place to start they will draw up the nessessery design documentation so you can get approved by building control it might cost as little as £150.
You by no means need to do this but if you are not confident and know the regs well it will actually save you time and money.