Building a Garden Office Advice Required

[jasonB]

If you have got bed rock then the piers can come off that. You are more likely to have a firm subsoil and will need a larger bearing area.

As a general guide as I don't know your soil something like digging a hole down 600mm that is 450x450. Pour 150mm of concrete into this to form a pad. You and stick a bit of rebar into that before it sets and this will tie the concrete tube infil to the base. Stand your tubes onto these pads and cut so all the tops are level and the shortest 100mm above ground level.

When set place a piece of DPC onto the top of the pier and then you can position your ring beam.

For a mono pitch the easiest way is just to make one long side taller than the other and have the ends with a sloping top. You can then either just fix joists to the top of the 2 long walls and cover with ply and felt. Or you could think of using a profiled metal roof, these can be had with rigid insulation bonded on and may well span the 3.0m without any other support.

Jason

 

[Markymark]

Great. I would like the roof to be quite a attractive feature and when I was considering a pitched roof I was thinking of using wood shingles. Was the profiled metal roof the corrugated type? If I could get a multi layered roof covering so that if one perishes it has a backup. I will research roof coverings.

Great advice as usual.

Mark

 

[chipchaser]

Hi Mark,

Interesting photos but more info needed to advise in detail. I suggest you drive 4 poles, one at each corner into the ground where you intend to site the building. Tall enough to show the intended eaves height would be useful. Attach roofers tiling lath horizontal around the four sides starting at the highest ground level (GL). Measure down to GL at the 3 lower points and record the dimensions. Mark the eaves on your posts with a horizontal offcut of lath. Take a photo and post it, with your dimensions to GL, in this thread.

It would be useful to establish what ground you have so you can decide how you will make the foundations. I would dig a couple of pits one at centre of the high end and likewise at the low. The top 6” or so of soil is generally organic topsoil not representative of the sub soil, I would go down about 24”.

Mono pitch roofs can have more rise than you might want with some roof coverings. The appearance is always a personal matter but you have the planning height restriction to comply with. You mention wood shingles. Info on these here:

http://www.cedarbureau.org/installation ... page23.htm

The only problem with the info is that they (USA & Canada) use “exposure”, rather than cover, and pitch ratio (i.e. 3:12) not degrees but basically 14 degrees is absolute minimum 18 degrees safer in wet UK and personally I think they look better at more traditional pitches of 30 degrees and above. Shakes are riven, shingles sawn and all come in random widths. They can be a challenge to lay to ensure correct side cover.

Every roofing material has its minimum pitch, generally smaller units must lie at a steeper pitch to exclude water. The corrugated bituminous sheets are cheap and easy to lay and seem less prone to leak than felt. If you use them provide frequent purlins, or battens if you use rafters, because they are prone to sag between supports. Better still lay them on a ply deck.

Hope that is helpful

Graham

 

[Markymark]

OK. Thanks for all the help so far.

The local Council have come back and rejected the Mono pitched roof option if the Eaves height is in excess of 2.5M from the ground. That being said I can have a dual pitched roof with a height of 4M and a eves height of 2.5M. Now I assume the dont mean the ridge height?

I have to talk to them with regards to which part of the sloping ground they are taking their measurements from. I will assume it is the lowest ground level.

I feel that a eaves height of 2.5 M on a mono pitched roof will feel claustrophobic as I am 6' 3". With a dual pitched roof the feeling of an open pitched roof would allow extra space.

Mark

 

[chipchaser]

Hello Mark,

the rules allow you to have a maximum eaves height of 2.5m and highest point, which will be the ridge, of 4m with a dual pitch roof. Any other roof form the max eaves height is still 2.5 but max overall height is 3m. If you are within 2m of the boundary the maximum height is 2.5 metres.

This pages sets it all out, with pictures if you click on the mini guide:

http://www.planningportal.gov.uk/englan ... buildings/

Conservation areas, curtilage of listed buildings, etc have stricter rules but your planners should tell you if any of those apply to you.

2.5m is over 8' and if you have a good overhang at the eaves the internal height should be comfortable. What would your minimum acceptable internal height be? You could have roof trusses like this and board below the rafters.

Eaves height of this turned out at 2.4m and internal height below the truss is 7' 1.1/2". But I am 6" shorter than you.

Have the planners actually been to site? I do think the suggestion of marking out with poles is worthwhile as if they come they can see exactly what you propose and confirm what they would expect, most critically where they intend to measure the eaves and ridge heights and so relative to what ground level. If they don't come you can drop a photo into them. Getting the planners on your side at the start is much less stressful than the fallout that can arise if a misunderstanding comes to light when you have finished your build

If you are not keen to mark the eaves height then at least setting the position and floor plane with shorter posts and confirming the fall of the site is worthwhile.

Regards

Graham

 

[Markymark]

Thanks Graham

Your shed looks great. Nothing as fancy for the roof. I wonder if the planners would visit the site as I have not paid anything in to the pot. I submitted a Household Enquiry form with all the details on it and they sent me a letter. I can talk to them on Monday. I will see what they say.
I feel a dual pitched roof will be easier to finish and will look better. I was considering Wood shingles which are difficult to install but look great especially in a woodland setting. I think I read somewhere that the minimum pitch needs to be 6/12 which on a 14 foot length would mean a ridge of 3' 6". Add that to the 2.7 m eaves height and I should be well within the permitted development rules. I feel i will have to explore the levelling of the ground or at least digging out the upper slope so the front elevation will be 2.7m to eaves also.

Getting itchy feet at the moment and want to start marking out. With posts as you suggested. My only worry is that if I have to dig out the upper slope I do not damage any of the tree roots.

Mark

 

[chipchaser]

Hello Mark,

And thanks for the kind comment. Its all clad and being used and one day soon I will finish the inside

You are right, if they have replied and made their comments you shouldn’t have anything to worry about except to confirm which ground level they would measure the eaves and ridge height from, if they ever bothered to check.

Aesthetics are very personal but I agree with you that a traditional pitched roof looks better than a monopitch in most situations. The summerhouse above has cedar shingles which I got from a place in N London, the cheapest I could find but still about £550 collected.

6:12 is 25.5 degrees which is ok for shingles and most alternative shed roof coverings. UK sheds generally tended to have the ridge running along the longest dimension of the building, in your case 14’, to minimise the rafter span whereas garden chalets seem to go the other way which I think is what you intend from the span and rise you mention above. Either work ok. If you use purlins to support the rafters you shouldn’t need ties between the rafter feet on a small building like yours. If the purlins are set at the slope of the roof you don’t need to cut any birdsmouths in the rafters so the carpentry can be really simple. If it is all to be insulated and clad internally, so concealing the carpentry, then galvanised pressed metal clips are quick and adequate to fix rafters.

The point foundations mentioned in earlier posts would minimise any damage to tree roots and, if taken deep enough, avoid later problems that could arise from the trees. You mention above 2.7m at eaves plus approx 1.075m (3’6”) rise to the ridge giving a ridge height of 3.775m. If the fall of your site is less than 0.225m you shouldn’t need to dig out the upper slope. Does your 2.7m dimension allow for the floor structure being above existing ground level?

Apologies if this is stuff you already know/have worked out.

Graham

 

[Markymark]

Hi Graham

Sorry for the delay..Making the most of the good weather.

I was going to use a ridge beam supported at both ends and nail the rafters to the ridge beam. I assume I would need to do the bird mouth cuts also. My alternative would be roofing trusses not sure if to make them up myself, with the limited knowledge I have, or buy them in? I would like to make all I can as this is my first serious woodworking project I will learn along the way.

Even the terms Purlins, Rafters etc were a foreign language a few weeks ago so it lets you know how little experience I have had.

I am in the process of marking out and digging the holes for the piers.

I have had conflicting views on the timber to use. Some people say use Kiln dried timber some say air dried as there is less twisting and warping when it is outside and some just say outside stored tanelised timber. I assume I need different source for the externally faced timber and the internally faced timber?


The fall of the land is approx 15 degrees 1' 6" in 10', if that makes sense?

Cheers

Mark

 

[chipchaser]

Hi Mark,

Here is what I mean. Apologies for the cobwebs but you can see that the purlin sits on a sloping top rail in the first picture, which is how I suggest you might do it. Offcuts provided the blocks which locate the purlins. Your purlins would be closer together and it would be neater to just cut a length of timber into pieces to suit the purlin spacing and use them as solid blocking (noggins).

The second picture shows that where I added this box onto the end of an existing range I simply bolted a timber plate onto the external wall.

It is a very simple way to form a roof and this video shows assembly of a purlin roofed garage:
http://www.youtube.com/watch?v=0VOV2YvbIP8

 

[Markymark]

OK New year and my Garden office is underway. I have dug out the footings and filled them with concrete. Now I need to form some piers. The pads for the piers to sit on are approx 18" square with four reinforcement bars. I need either a square hollow concrete block to build a pier or some kind of Concrete former to either make a square or round 3' pier.

Does anyone know the best way to proceed and where I can get cardboard tubes from?

Thanks

Mark

 

[Mcluma]

OK New year and my Garden office is underway. I have dug out the footings and filled them with concrete. Now I need to form some piers. The pads for the piers to sit on are approx 18" square with four reinforcement bars. I need either a square hollow concrete block to build a pier or some kind of Concrete former to either make a square or round 3' pier.

Does anyone know the best way to proceed and where I can get cardboard tubes from?

Thanks

Mark

I have to check where i got them from, they work perfect, you just cut them with the jigsaw to size

found it

http://www.essextubes.com/piling-pile-caps.html

 

[Markymark]

Great thanks.

 

[Mcluma]

I know its a bit late in the game, but this is the home office / cabin i build, this one has a masonette floor in it


dsc0097lg1 by mcluma, on Flickr

dsc0096ue6 by mcluma, on Flickr

dsc0090va5 by mcluma, on Flickr

dsc0088go6 by mcluma, on Flickr

dsc0087ir7 by mcluma, on Flickr

 

[Markymark]

Ok first dilemma.

I have spaced the floor joists at 600 centres but as the walls are going to be clad with ply i will have to do the wall frames at 2' centres to accommodate a 8' x 4' sheet. This presents problems in that the kingspan or equivalent insulation comes in 600 wide or 1200 wide sections.

The question is if I was to build a typical stud wall at 600 centres like the floor then the spaces between the studs would be 553mm that is a 600 centre less 47mm ( the size of the stud).

1106 or 553 would not fit any standard insulation in between.


Am i missing something?


MARK

 

[No skills]

Sorry being dim here.. what sort of insulation are you looking to install? something like celotex poly sheets are pretty easy to cut to fit between studwork.

 

[Markymark]

Celotex is easy to cut. I thought you could buy insulation to fit inbetween the standard size centres of a stud wall, whatever that may be.

I'm just lazy.

Mark

 

[Dibs-h]

Celotex is easy to cut. I thought you could buy insulation to fit inbetween the standard size centres of a stud wall, whatever that may be.

I'm just lazy.

Mark

The insulation that is 450 or thereabouts wide is really for rafters. As it's precut, works out slightly more expensive. Jsut get the 8x4 sheets and cut it to fit.

HIH

Dibs

 

[Markymark]

Thanks for the advice.

I feel this is the only viable option.


Upwards and onwards.

Mark

 

[Markymark]

Ok, I need to clad the timber frame walls to make them rigid. I was going to clad in 11mm OSB as I have budget constraints.

Question is, is 11mm OSB sufficient? Or do i definitely need 18mm? Should I brace any of the four timber frames diagonally and if so can I just brace in between two studs on each frame?

The shed is currently 5m x 4m and in a windy elevation.

Thanks

Mark

 

[No skills]

Depends on what you want to hang off the cladding, 12mm is fine but if you have something especially heavy to put up and you cant hit the studs with the fixing screws then an upgrade maybe in order - if you do have to upgrade in thickness for some reason then perhaps you can get away with just doing one wall in the thicker material. Have you put any noggins in between the verticle studs?

** sorry just thought, is this for inside or out?? #-o **