Brick garden office with cavity/Help required for materials

[mpheating]

Hi all,

I want to build an office in my garden, the dimensions are going to be 5 metres (length) x 3 metres (width) x 2.5 metres (height)

I want a 100mm full fill cavity (got the insulation cheap)

I have 1400 brand new bricks, I want the front and one side brickwork, which will include a window and door at the front, and a smaller window on the side. The other walls and inner walls are to be dense breeze blocks.

My question is, how many breeze blocks will I require and how much sand/cement.

I am going to insulate the floor with 100mm kingspan and screed over it, how much concrete and hard core would you say I require?

The roof is going to be insulated with kingspan and done with fibreglass (my cousin is a roofer)

I have dug footings 450x450 hoping this is going to be enough, I am wanting to buy all materials as I have accounts and then get a builder in to carry out the professional look, just trying to save a bit of money as we have our second child on its way.

If you could help me it would be much appreciated.

Many thanks

 

[mpheating]

can anybody help

 

[conny]

A lot of people will be at work at the moment.
Best hold on till later today/this evening when I am sure you will get some replies.

One of the first questions you are likely to be asked is do you have planning permission.

 

[BigIan]

I want a 100mm full fill cavity (got the insulation cheap)

I assume that the unsulation is suitable for full fill cavity?

I have 1400 brand new bricks, I want the front and one side brickwork, which will include a window and door at the front, and a smaller window on the side. The other walls and inner walls are to be dense breeze blocks.

My question is, how many breeze blocks will I require and how much sand/cement.

Wow, this is like a maths puzzel from school,

In short you have 40m2 of masonry per skin above ground + another block and a half allowance to get from the footings to ground level.
this equates to 40+5 = 45m2 per skin. so 90m2 in total.
You have 21m2 in bricks after removing a roughly 10% wastage.
90m2 - 21 = 69m2 there are 10 blocks in a meter so you will need roughly 690 blocks. (i`ve included a 10% waste in there too)

As for the mortar

1m3 will lay roughly 1500 bricks,
and 1m3 will lay roughly 1500 Blocks.

1m3 of mortar will require aproximately 3 tons of sand and 30 bags of cement.

For your 1400 bricks you will require 1 m3 of mortar

for the 690 blocks you will require 0.5m3 of mortar

this will equate to 5 ton bags of sand, and 45 bags of cement, roughly depending on how neat your brickies are.

I am going to insulate the floor with 100mm kingspan and screed over it, how much concrete and hard core would you say I require?

The roof is going to be insulated with kingspan and done with fibreglass (my cousin is a roofer)

You will need to lay the kingspan on some form of slab otherwise the screed will break as the kingspan moves and settles.

I would recomend:

150mm depth of H/Core
= 5*3*0.15= 2.25m3

100mm fibre reinforced concrete laid over 1200 gauge visqueen
=0.1*5*3=1.5 m3

60mm fibre reinforced screed
=0.05*5*3 = 0.75m3

I have dug footings 450x450 hoping this is going to be enough, I am wanting to buy all materials as I have accounts and then get a builder in to carry out the professional look, just trying to save a bit of money as we have our second child on its way.

Your footings will need to be down to a suitable strata to bear the load (normaly firm clay) as for the 450 x 450 footings these are more than adequate to support a 300mm wide wall. again asuming they are down to a suitable strata.

Your planning officer should have adived you as to the type of footings you need?

 

[skhudy]

One of the first questions you are likely to be asked is do you have planning permission.

2.5m height and only 15m2 floor area is one of the things you can do without planning permission as long as its less than 50% of your garden http://www.homebuilding.co.uk/advice/project-tips/planning-permission/no-planning

 

[michaelbailey]

try gain later

 

[michaelbailey]

planning should `nt be a problemm but i`d get written confirmation from the council to make sure and get names keep a diary the foundations arenormally checked by the "BCO" in building control but they only get involved when the project is to be habitable. although planning and building control atyour local town hall are all probanbly on the same floor . they are separate bodies.
i`ve just completed this one for a mate of mine.
a9x8 72 m2 775sq.feetmeter single story traditional brick built £29,000=approx.£402 per m/2. 37£ per sq ft designed to individual timber frame £19,300=approx.£306 per m/ 21£ per sq ft designed to individual specifications. to include a basement in this build . add 17000£ if constructed in class`b` engineering brick.+plant hire for excavation and spoil removal.=23.60£ perm2 22£ per sq foot. i am a building cost analyst and have copies of drawings and project management spreadsheet. if you want to have them . no charge or any obligations i can easily forward them to you via email free.they may be of some help.

 

[conny]

Looks like you have come to the right place mpheating!

Good on you Michael.

 

[mpheating]

hi all, thanks for your response.

I have read on the internet and have been told by one builder I don't need planning permission due to the floor space been below 15m2 and the roof height not exceeding 2.5 metres.

The cavity wall insulation I have got is for full fill cavity walls yes.

Ian,
As for the floor, originally I was going to carry out this build myself but im a plumbing and heating engineer not a builder, and I guess its every man to its trade...but I was going to lay my foundations, dig out the centre and add hardcore, waker plate the hardcore down, add some sand and then a membrane sheet, then 100mm insulation and screed on top. will this method not work? I presume a builder will know what to do anyway...?

I have priced up 700 blocks, 5 tons of building sand and 45 bags of cement and it came to £970 inc vat...does this sound about right?

Thanks for all your help

 

[trowlerman]

for 1500 bricks = 1.5 ton

for 700 blocks = 0.7 ton

so I would go for 3 x tons bags

and 25 bags of cement

5 litres of febmix

 

[mpheating]

im confused lol

how can it go from 5 ton to 3 ton and 45 bags of cement to 25...

obviously the less the better for me, and I don't want to place the order and be left with loads of excess materials...

is the above materials not allowing for foundations and floor

 

[trowlerman]

my estimates are for brick and blockwork only

 

[michaelbailey]

hello again
I don't know how far you`ve got with your project . but I have designed and built garden offices/rooms for both self build and builders and they are used fo many things . think before you build it, do you want to have a power source /heating / sanitary facilities . get your project plan sorted before you start. unfortunately I am now retired , but given your details I will put together a project for self build. it`ll keep me quiet for a bit and the missus

 

[mpheating]

trowlerman, thank you very much thats spot on


michaelbailey, that would be great. a project plan would be great.

I have an electrician to put power, sockets and lighting in etc, i am going to have a wall heater in there to begin with, but at a later stage may run a gas pipe from my property and have a little boiler in there with a radiator (as im a heating engineer) wouldn't cost me that much.

 

[michaelbailey]

same as a static van great all you need