Garden office

[Nickholby]

Hi

My first post so be gentle with me...I work from home and with an expanding family now means I must give up my office in the loft for my daughters bedroom.
My plan is to build an office at the bottom of the garden.my garden is approx 5 m wide so the building would be the whole width and 3m deep, my plan is split it into parts a small part being a shed and the rest my office.
I have been looking at building it in block work with a cavity as It will be close to the boundaries on 3 sides and to get max size would not leave any space for maintenance of cladding etc..and I'm thinking the lack of air circulation would mean damp conditions and rot the wood..
I was thinking concrete blocks on the external wall and either thermalites or stud work for the international wall.
I would welcome any advise and pitfalls with damp proofing, ventilation etc...or could this be done in wood without a problem.. I like to think i am fairly handy so plan to do most myself and with friends and have plenty of time...Many Thanks..

 

[PrenticeBoyofDerry]

Have you planned for services such as electric and water?

 

[Nickholby]

Hi

Im not planning for water but electrics i have...when i had a rear extension i laid a new big cable out to an outside socket so will use that.

Im more concerned to whether i can build from wood or not with the building being right up against the boundaries on 3 sides and then will not be treatable or should i stick with the block work idea...only thing with the block work i will end up losing space with the 2 skins.

 

[Mursal]

Timber built with a single skin block exterior. It will give you all you need, with simpler construction.

http://www.finehomebuilding.com/pages/how-to-build-a-shed

More stuff
http://bit.ly/1ag5heK

 

[pinenot]

If your so close to the boundary on three sides, how will you build it? and if it's a case of building against an others wall you will surly be required to advise them as they would require those same maintenance rights you are querying here!! ...pinenot

 

[Nickholby]

Hi

Thats another reason for building in blocks can work from the inside, plus im sure my neighbours either side of me would let me temporarily take the fence down. so just the back wall to worry about.. if done in wood could make up panels for the 3 sides... just worried it might rot too quickly..with not much air circulation and no real way to treat regularly..unless i leave enough gap to treat from the roof or sides with a roller on a pole?

Ta

 

[pinenot]

I would suggest before you put the neighbors fence back up, you roughcast the wall...pinenot

 

[ban-all-sheds]

And ask them what colour they would like it.

Ask them if instead of replacing the fence they would like you to fix trellis to it so that they can grow climbers up it (but get expert advice on how to ensure that the original boundary remains in force & documented).

Ask them, if they provide the power, if they'd like to put lights on the wall for their garden.

Anything, really, which makes BA difference to you but might improve things for them.

Re timber - AIUI, unless it is at least 1m from the boundary you'll need Building Regulations approval unless it is substantially made of non-combustible materials.

Finally - you will want insulation. It will be much easier to put this on the outside of the walls than on the inside.

 

[Nickholby]

Hi Thanks for your replies on this.

My thinking now is for a block outside wall with small cavity and then timber stud wall made from 3x2 with insulation in the stud work.
Will that be enough room to insulate sufficiently.
The roof span front to back will be 3m whats the min size rafters i can use for that?
Trying to keep ceiling height as high as possible as building will have to be max external height of 2.5 m.
Roof will be boarded and felted or possibly a sedum roof.
Are there any other possibilities, seen garden office companies using ready insulated panels.

Will i need building regs as i have internal timber wall?

Thanks

 

[CaptainCaveman289]

You don't need building regs less than 15sq m.
You can also build within 1m of the boundary in substantially combustable materials if the height is less than 2.5m, so fits in nicely with permitted development.

How much space do you need for your office, could you stand to lose a little width to retain maintenance access? If you have an airgap properly treated wood shouldn't cause an issue, raising timber off the base helps too.

I'm building a similarly sized workshop at the moment out of brick, block and timber:
//www.diynot.com/forums/your-projects/post-beam-garden-motorcycle-workshop.377379/

Hope it can be of some use.

 

[Nickholby]

Thanks for your reply and your interesting project..

Good to hear that i wont need building regs so i will probably go with block outside wall with cavity and stud internal wall.

Should the cavity be a mininum or is any size gap ok?

also should i tank the inside of the block wall with some sort of paint to prevent damp? i will be putting in a DPC though.

How thick should the slab be?

Ive asked this before but what is the min rafter thickness for a span of 3m for the roof.

Thanks

 

[CaptainCaveman289]

0-15 no building regs, 15+ they kick in.
Additional caveats apply, e.g. If it's attached and heated it's counted as habitable and therefore BR apply.
It's a minefield, I'm by no means an expert, its worth a peruse of the BR & PP section as there seems to be a few knowledgeable folk there.

Cavity I suppose is spaced to whatever the insulation slab is, i.e. 60mm?
Don't forget to tie in the courses.
Could you put insulated studwork against a single skin?

For waterproofing it really needs to be from the outside, airated concrete blocks are like a sponge, you will have trouble with damp & mould.
If you can maintain exterior access you can paint blockwork and give it an occasional rinse and scrub.
With timber frame you can weatherproof in sections before erection (fnarr).
Overhangs and good drainage help.

My slab is 4" straight onto soil (via DPM) as I know it'll work here for my application.
Many go for compacted hardcore with 6" slab ontop!

There's a rafter calculator somewhere on the web, depending on your coverings I imagine 100-150mm should more than do the trick.

I'm using 100mm & 75mm (1:3) with noggins for a 2.6m near flat span and laying t&g ontop because.overall and head height are very tight, but it should do the trick.
Look at a cheap sheds, they get away with building them from twigs!

Essentially the more shallow the section, reduce the spacing accordingly. I'd happily jump up and down on 50mm rafters at 600mm with 12mm ply skin (thats what I built my last workbench from, and thats how I tested it!)

 

[ban-all-sheds]

You don't need building regs less than 15sq m.

Then why does it say, in Schedule 2, that the limit for a Class 6 exempt building is 30m²?

You can also build within 1m of the boundary in substantially combustable materials if the height is less than 2.5m, so fits in nicely with permitted development.

And why doesn't it mention that height factor when talking about distance from the boundary and combustible materials?

Where are you getting your information from?

 

[CaptainCaveman289]

You don't need building regs less than 15sq m.

Then why does it say, in Schedule 2, that the limit for a Class 6 exempt building is 30m²?

You can also build within 1m of the boundary in substantially combustable materials if the height is less than 2.5m, so fits in nicely with permitted development.

And why doesn't it mention that height factor when talking about distance from the boundary and combustible materials?

Where are you getting your information from?

Exemption class 6,1 (>30sqm) only applies when the building is 1m from the boundary,
if you're within 1m the applicable exemption is Class 6,3 which is >15sqm,
the OP described his intention to build across the entire width (less than 1m clear of boundaries), therefore he is working under exemption 6,3 not 6,1.

Admittedly I could have phrased it better initially.

My bottom of the garden shed also houses motorbikes, so I think I've picked up the height vs combustable materials vs distance from boundaries from the garage regs and got it mentally intertwined with other bits, but as I said in one of my posts, I'm not an expert.

Some of my info I get from forums (which are generally full of enthusiastic ameatures like myself who are occasionally mistaken) some I read from official sources,
Exemptions here ref 15/30sqm:
http://www.legislation.gov.uk/uksi/2010/2214/schedule/2/made

 

[CaptainCaveman289]

Re timber - AIUI, unless it is at least 1m from the boundary you'll need Building Regulations approval unless it is substantially made of non-combustible materials.

Where are you getting your information from?

Ahem