Barn conversion

[Bodidly]

Hi

I am considering  posting up the process we went through in converting a barn to a home. My typing skills are sub normal but if others would find a description and pictures of the construction  process useful I would be happy to do this.

If you are interested  please say and let me know what you want to know.

Beau

[charlieb]

Yes, definitely interested Beau. Interested in high level stuff - overall cost in tens of k, etc, - because there's a steading on the farm at home that could conceivably be turned into homes (or offices/farm shop/WWOofer dorms).  But also interested in the geeky detail because I'm geeky. Things like how you put internal insulation next to an old stone wall, and whether it's possible to retain crooked roof beams and still get a watertight new roof (most of the charm of old agricultural buildings is in the crooked-ness).

[knighty]

I'm interested too.... always nice to have a nose :-)

[wattmiser]

Hi Bodidly , bring it on ! as I am refurbing an old stone building with no foundations and flag stone floor 
i am very interested

[Bodidly]

Hi sorry for taking so long to come back to this I have been looking for photos of the barn prior to starting work and have failed.

Background

I live on my parents smallholding where I work as a cabinetmaker. When I got married my parents gave me the barn to convert.

Planning permission

We live in Dartmoor national park so this could have been tricky.  We employed an architectural consultant for the drawing and to deal with the national park. Permission was granted on the bases that it would be an annex to the main house.

The building

It is 22m long and 5m wide running north-south. The walls are granite faced with rubble infill approximately 600mm thick. We got permission to raise the walls to get 1 1/2 story's in. In working out internal layout I made a scale model to help visualize how things would work this I found very helpful.
 



Ground-works
Nothing can prepare you for how much earth comes out of hole in the ground!

The first major job was to dig out the concrete floor I had put in when it was my workshop. I started with an SDS drill and a pickaxe but soon moved onto a 3 tonne digger with a pecker on the front. Then we dug down a bit more as we needed to lower the floor to get two stories in; this new level was at the bottom of the barn,s foundations. At this stage I contacted my building control officer (I had visions of having to underpin the whole place) but he took a look at it and said it had stood for 200 years and was still standing so don,t worry just make sure the floor slab supports the foundation stones  phew.

More later
Beau

[Bodidly]

Hi again,

Wife's typing (Hi guys, I'm Liz) so things should go a bit swifter now (or verbal diarrhoea, depending on your viewpoint). 

So now I've torn up the floor and dug down the foundations.  The next thing is drains - everybody's favourite!

We got lucky with the foul drains as there was an ancient spur off the farmhouse's septic system which was unused but serviceable so we could tap into it without digging up the farmhouse - we had 2cm of fall to spare.  The rainwater was much more complex as there was no existing structure for getting rid of grey water on the farm and the house and barn occasionally flooded with field run-off.  Our farmer neighbour visited when the barn was under water and said he was happy for a new drain to go into his field.  This involved digging over 100 meters of new drainage at a meter depth (and deeper).  It became a major project in itself.  I did this on a shoestring in mid winter using a minidigger for a short time and lots of digging by hand.  In hindsight it would have been far more efficient to employ a skilled JCB operator. Minidiggers cost about £150 for the week, the JCB operator cost £170 for the day and did more than me in a week and I was free to do my own thing while he got on with the job.  We did not discover this till after when landscaping.

I was not prepared for the volume of earth which came out of the trenches and it was a surprise how much pipe bedding is needed.  The farm yard looked like a battlefield for months.   All of these things may be straightforward to an experienced builder but this was my first building project and there was much head scratching and book reading.  I ended up with 3 books - the housebuilders bible, the building construction handbook and the building regs book which were my night-time reading throughout the build. 

That's drains (for now).  I'll post this and carry on.

[Bodidly]

Waterproofing

I had discussed different ways of waterproofing the barn.  The traditionalists would say lime point the outside and lime render the inside with no insulation but I would get away with this for building regs as it is a conversion.  The architect suggested building an internal wall with cavity inside the building.  I was not happy with either of these.  I grew up in a cold damp farmhouse and the traditional way would have lead to this (or divorce).  The internal wall solution would be fine in a wider place but the barn was already on the narrow side.  My solution was to point the outside with lime as the walls move a bit anyway and lime, I'm told, copes with small movement.  Lime also lets the walls breathe - I do question the wisdom of this when back in year 2000 we had 100 consecutive days of rain so I don't know on which one of those days the walls were supposed to let the water out again.  On the inside I used a polypropoline tanking membrane designed for underground basements for the full height of the walls,  this may be overkill but I was taking no chances (wife was traumatised by damp farmhouse).  The lowest strip of the membrane was put against the walls before the floor slab went in so that any water that ran in through the walls could drain into a french drain which was dug underneath the floor slab (see photo - sorry about my arse - says Liz)


Over the french drain we laid recycled hardcore from digging out the inside of the barn and then blinded with soft sand then a traditional blue dpm lapping up above finished house floor level and finally the concrete floor slab was laid on top (which you can see going in in the photo above).  This felt like a real land mark as we were now out of the mud.

At this stage we had left the old roof on even though it was going to be replaced due to the raising of the walls and the pitch being too low, not to mention the wood worm.  This was the next job.

[biff]

exellent,
       keep up the good work,
                                         biff

[Bodidly]

Roof off

We took a bit of care as the corrugated was kept for roofing future farm projects - log sheds as it turned out - check out lizlogs.co.uk if you're interested but we are sold out for this year.

Openings and lintels
We replaced all lintels as they were wooden and rotten.  I was told to expect the walls to collapse above the lintels and as most were very close to the top of the wall I did not try to support them and to my surprise virtually nothing fell down.  We used several concrete lintels for each opening with an external L section of oak 50mm thick to face concrete lintels on the outside.  I did not want solid oak lintels as wood will expand and shrink leaving cracks in the wall.    

Next was to extend the tanking membrane up to the top of the walls all joints carefully taped with mastic which we are assured will last a good long time. At this stage I did not know about the advantage of airtight buildings and thought this was overkill to please wife (still traumatised living in damp farmhouse) but now I'm glad I did this as it makes the house airtight as well as damp proof.  The mastic is very difficult to use in cold conditions as it just does not want to stick to anything so I had to heat it and the membrane with a heat gun to get a good bond.

Next was the upstairs floor joists.  Not wanting to make big holes through the tanking the timbers were suspended off L section steels which were injection resin bolted into the barn walls.  I am counting on the resin sealing the hole through the tanking.  The floor joists sit on the steel.  This was a very quick way to get floor joists up in an uneven and weak walled barn.  I am evangelical about injection resin; the mortar between the stonework on the inside of the barn was very weak but I did not have a single resined bolt move when tightening.  Something I would say when taking on projects like this is a good powerful SDS drill is worth its weight in gold.  I bought a Makita supermac and used and abused it and it takes it all.  

I then built up the internal block walls.  In hind sight I should have made any non supporting walls out of timber stud with soundproof insulation as the block walls seem to carry sound - I'm not sure about this though - any comments?  

Next extending up the external walls (and rebuilding one section which was leaning 200mm out from the line of the rest of the wall which was very straight).  we had saved as much granite as possible to reuse.  This was a slow process as a lot of mortar is needed with uneven granites.  Also I was most uncomfortable with the "wet" trades.  When building up, I would scrape out the outer 40mm of mortar to point later.  I was able to get good advice on this as an old school friend is an excellent stone mason.  

More later.  

Beau

[Bodidly]

Roof on

First job was put a wooden wall plate on. This was 9"x3" held down with m12 stud bar and more of my now best friend the injection resin. Great care was taken on getting all the plates level and parallel to make the roofing as simple as possible a good laser level proved a fine investment to help this. The roof itself was done in two different ways .In the double height open plan area I made traditional A frames  made of larch this had at least a nod to the old structure we had removed.  



Over the 1 1/2 story end we put up a steel I beam to support the rafters.


Sorry about the quality of the pictures they are digital pictures of a photo

In the first picture you can see that perlins are suspended from steel plates between the A frames, this was to keep the overall height down to comply with the planning permission.
  We chose larch for a lot of the structural wood as it was cheapish and relatively rot proof were  exposed to the elements. We would have loved to use oak but it was three times the price.BEWARE Larch proved a bit problematic it is supposed to be kiln dried Siberian larch but the large spacing on the growth rings suggested it was not grown that far north, secondly it was not very dry most of my kiln dried furniture grade timber from the USA is down to 10% but this was over 20% moister content  this meant having to leave it a while before doing the dovetails.

[Bodidly]

Having been careful getting the wall-plate parallel I pre cut all the rafters to length in the workshop then  nailed small strips onto the rafters to support the 50mm pur insulation. Having come from a background of making furniture I could not bring myself to use nails so all the rafters are fixed down using large spax pan head screws being careful to keep the spacing consistent. Next the insulation was again pre cut to width on the bench saw before going up on the roof. all joins were then taped with 100mm foil. Do not do this in mid summer without sunglasses lets say I now know what snow blindness is and I don,t recommend it. Incredibly after taping the joints the roof was completely waterproof. Next was a breathable roofing felt with a double-sided tape to seal the lap this was recommended by the manufacturer but the roofing supplies had never herd of the using tape. At this stage in the build I was becoming more aware of the potential benefits of air tightness.
  Time to buy a nail gun. Next 25mm thick counter battens then packers to create the springing then the roofing battens, the nail gun did make this bit go very much quicker. The slates , I am ashamed to say,are Brazilian (it does seam mad that in the twenty-first century we nail rocks on to keep the water out) it would have been nice to use local slate but Delabole was something like £4.50 each verses 70pence for the Brazilian.

 
I have never done roofing before so quite a bit to learn. First the Brazilian slate is very hard so it has be cut with an angle grinder not a slate hook secondly I did not realise the thickness would vary so much. To start with I just nailed them as they came but soon discovered it looked much nicer to put the thick ones at the bottom and thin ones near the ridge.. Oops nearly forgot the roof lights these had to be of the conservation style to please the national park. The ones they like are steel so very heavy and as it turned out dreadful for condensation I would never recommend them to anyone. I wish had fought the park on this one but that's hind-sight for you.


 
OK that,s all today
Beau

[clockmanFR]

My hat is off to you.

Its so damn good to see someone actually doing everything. 

Its what life is about?

Blood sweat and tears. Mostly my blood as in every building i do there remains a cut finger/arm/leg etc, to give that personal touch, i tried to power screw a screw through my finger yesterday. 

[Bodidly]

Thank-you for encouragement biff and clockman.
My good lady wife has found some missing photo,s but still non of the barn pre works.



The. main farm yard and access to the fields.

The remains of my very understanding parents lawn.

[Bodidly]

Walls

This is not a conventional solution but so far it has worked.

Horizontal 25mm x 50mm roofing batten were fixed with adjustable screws like these http://www.locksonline.com/acatalog/adjustable-screws-6-0-mm-6299.html

Into brickplugs designed to go with the tanking membrane like these http://www.treatdamp.co.uk/prod/oldroyd_membrane_brick_plugs.html
some of the plugs did need some injection resin were they were in pointing but you can see enough through the membrane to work out were the solid rocks are.

The adjustable screws allow you to screw into the wall and batten. When the head has sunk flush into the batten  the rings around the head grip so you can now unscrew to adjust spacing from wall and the batten stays fixed onto the screw (this all works best when the batten is new and wet) The screws come in various lengths so you can work round fairly major wall variations. The battens are at 600mm centres.

The insulation I used was a multilayer foil this was just stapled back to the battens. Then all joints were taped with foil tape and the tops and bottoms were sealed with either tape or expanding foam. Next more roofing battens fixed vertically at 400mm centres these were screwed back through the foil to the horizontal battens. The manufactures of the foil recommended nailing but if you sandwich the foil tightly it does not get wrapped around the screws.

Then in our open plan dining/kitchen/living area we put up 11mm OSB board and then plaster board.  The OSB enabled any subsequent fixings to the walls to be very easy.  In all other rooms we just put up plaster board. 

Beau

[JohnS]

Then in our open plan dining/kitchen/living area we put up 11mm OSB board and then plaster board.  The OSB enabled any subsequent fixings to the walls to be very easy.  In all other rooms we just put up plaster board. 

Beau

Instead of OSB and plasterboard, you might want to consider using Fermacell boards.

John