Hanging by a thread

The 2nd and 3rd Velux windows are now fitted.  Hurrah!

Fitting the 2 larger Veluxes was essentially the same process as the 1st smaller Velux.  However, i didn't have the luxury of having an existing opening (skylight) to work from, which meant that i had to go out onto the roof to strip back the slates.

The roof is quite steep, not quite as steep as this photo suggests, but steep enough that it was impossible to sit on without sliding down it.  So, as well as wearing a full body harness with a fall arresting inertia reel, i had to use a rope in which i tied foot loops.  So, whilst sort of sitting-laying on the roof with the sole of my foot in the loop i started stripping the slates where the Velux was to be fitted.

Once enough slates had been stripped i was able to cut through the sarking boards and felt to form an opening large enough for me to fit through.  This meant that i could strip the rest of the slates and form the full opening from the relative safety of the loft.  Forming the full opening was covered in my previous post, so no need to bore you with that again.

As before, the sash was removed and the frame was fitted into the opening with a 20mm clearance all round as per the instructions.

The Velux is secured in place by these large brackets which are screwed onto the frame before fitting then screwed through the sarking into the doubled up rafters.

Felt is fitted up against the frame and i have also sealed this onto the frame using roof sealant.  This isn't strictly necessary, but i wanted to reduce the risk of leaks at the rear elevation windows in particular as it's less sheltered than the front and exposed to high winds and driving rain.

The flashing kit is has to be ordered over and above the main Velux window and it's an extra £60, but it's well worth it as each part fits accurately, providing a good weathproof seal.  The kit comes in 4 main parts, top, bottom and two sides.  The top and bottom flashings are large single piece, shaped metal sheets which are fitted to the Velux frame and then slated over, with the bottom flashing creating a 6 inch apron for weathproofing.  The side kits come in 7 pieces per side and each one overlaps the other with the 'tangs' folded down to hold it in place.  A capping piece is then fitted up the edge of the frame and this capping piece covers the upstand edge of the flashing pieces.

There appears to be two ways to fit the flashings, one is the way i've done it and the other is to overlap each individual side flashing with a slate.  i.e. alternate flashing, slate, flashing, slate.  I preferred to fit the flashing as one piece before slating it in as i believe this gives a better seal to the roof felt and reduces the chance of wind driven leaks. The slates on the rear elevation of the roof are easily twice the thickness of modern slates and overlapping them with the individual flashing pieces would have meant they would have sat higher than the edge, which would have made fitting the capping piece almost impossible.

 

And here are the two rear Veluxes fitted and slated in place.  So far there's been a few good days of heavy rain and no leaks, so it looks like the job's been done well.

I'll be back out on the roof in a while to fit the slate vents, so i'll be keeping my harness, inertia reel and rope handy, because falling 30 feet might sting a bit and may leave a nasty bruise!

Let There Be Lux

And the weather and Greenwich Mean Time combined to say "Let there be light," and there was.  I saw the light and it was good.

And it came to pass that the first of the Velux windows was fitted.

The timber bridles to form the opening for the Velux window had to be doubles up and i glued and screwed them together for additional strength.

The bridles had to be hung on the doubled up rafters using joist hangers.  The cut rafter ends also had to be hung on the bridle using joist hangers.  These were fitted before stripping out the existing skylight and creating the larger opening for the Velux. 

Even the small Velux windows (960mm x 600mm) are quite heavy, but thankfully the window sash separates from the frame quite easily.

To remove the sash on this top hung window you simply open the window fully using the bottom handle, then pull down fully the ventilation strip and spin the window a full 180 degrees.  This exposes the hinge and the securing pin.

Once the securing pin has been pushed in, the window can then be lifted out of the sash and laid aside.

Now that the rafter has been cut, the bridles fitted and the Velux prepared for fitting the window opening can now be formed.

Forming this opening was relatively simple as there was an existing skylight, so it was simply a matter of leaning out, stripping back the slates and then cutting the opening to the correct size.

The sash is fixed in place by screwing through the external brackets into the rafters.  Externally, there is a flashing kit fitted around the sash which is then slated over to provide a waterproof finish.  Daylight was fading fast at this point, so i didn't stop to take many pictures.  However, i've two more Veluxes to fit, so there'll be detailed pictures in a future post.

Re-fitting the sash was the reverse of removal, with the hook part of the sash being inserted into the frame hinge mechanism and the locking pin being pressed into place.  Then the sash is spun 180 degrees into place to its top hung position and closed normally using the handle.

The job took about 6 hours in total, which is not too bad for fitting my first Velux and doing my own slate work.

The Road to Partition

Divide and rule

The chimney breast partition had to be double sheeted with 12.5mm plasterboard, with the joints staggered.

As well as being screwed in place the 2nd layer of plasterboard was also stuck on with grab adhesive for good measure.

I've only double sheeted the right-hand side of the chimney breast partition to allow the en-suite partition to be constructed.  The left-hand side has been left un-sheeted just in case the Building Standards Inspector wants to check the insulation at the partition at the next stage of inspection.

The first part of the en-suite partition was then constructed using 3" x 2" timber, allowing for the door opening and the double thickness timbers at the rails, cripple studs and lintels.  The return leg of the partition will be done once the en-suite Velux is fitted and the full depth of insulation fitted at the ceiling and the walls.

Interstitial Condensation Elimination (aye, interstitial)

Well it's a new year and i've had a good festive break, but now it's back to work and my goodness there's still plenty of it!

The Velux windows are still not fitted and it doesn't look like there's going to a decent window in the weather for months to come, so i'm going to push on with some bits of internal attic work which can be done to progress things.  

The second layer of 80mm insulation board was fitted to the hip elevation of the roof and was also fitted to other parts of the roof where it would not get in the way of the future fitting of the Velux windows.  

I applied a grab adhesive (Gripfill) to the back side of the boards which means that the boards are now glued to the roof trusses and to the 80mm boards which were previously fitted inbetween the roof trusses.  To provide additional securing i cut some 100mm x 50mm packers and screwed through these with 120mm size 12 screws into the roof trusses.  Eventually the final plasterboard sheets will be fixed to these insulation boards and i will use the same Gripfill adhesive and screws to defy gravity.

To allow me to construct the partition for the en-suite i would have to complete the works to the party wall.  This meant that I would have to fit the air-vapour control layer then two sheets of 12.5mm plasterboard.

The air-vapour control layer is a reflective breather membrane which is airtight and vapour tight.  The reflective element reduces heat loss, the air tight element eliminates draughts and the vapour barrier aspect prevents vapour, in the form of condensation, passing through into the wall and insulation where it would condense into water and cause rot, damp and mould growth.  The entire 'box' of the loft conversion will be wrapped in the air-vapour control layer prior to the fitting of the final layer of plasterboard.  This will prevent interstitial condensation (aye, interstitial).

 Each of the joints of the air-vapour control layer were overlapped and sealed using adhesive aluminium tape.  And yes, my American friends, that's Aluminium with 2 letter 'I's.

 The first layer of plasterboard was fitted and screwed in place.  The second layer will be fitted shortly and will be positioned to ensure that there are no overlapping joints vertically or horizontally.

Inception, Initiation and Indication of Insulation Installation Information

It's getting to that stage of the job where what would normally be large stand alone jobs have to be split into smaller parts to allow related works to be progressed.  In this case, i need to complete the construction of the party wall to be able to construct the en-suite partition, which in turn is required to allow the electrician to finish his first fixing of cable runs.  Normally the velux windows would have been fitted prior to the insulation being fitted to the roof, however, poor weather and limited daylight hours are making this difficult, so i'm pressing ahead with the fitting of insulation in particular areas.

Budget management is crucial and an opportunity arose to purchase all my insulation in one go at a very good bulk price.  The advantage of this is that I will have all the insulation to hand as each part of the job progresses.  The dis-advantage (for some) is the need to store all the materials. Fortunately i have sufficient storage space.

A 'local' company (20 miles away), Malcolm Insulation, was able to provide all of the insulation i needed.  The 80mm and 40mm sheets for the roof and oxter walls and the 145mm slab for the oxter and party walls.  The approved drawings recommended using Kingspan, however Malcolm Insulation supply Ballytherm boards and they were able to confirm that the U and R values provided the same level of thermal insulation as Kingspan but for half the cost.  They were even able to deliver within 24hrs of my order. Can't argue with that!

Quite a pile of insulation.  Fortunately, the garage was able to hold it all.

As you will recall from the previous post, the party wall partition was to be insulated on the back side, with a 25mm gap to be maintained from the party wall.  The 40mm boards were secured in place using 'No More Nails' and as per the picture below, the 25mm gap was maintained.  80mm insulation boards were also fitted to the roof rafters.

25mm air gap between party wall and partition

The 80mm insulation boards were cut and push-fitted between the rafters on the roof side.  A 50mm air gap between the underside of the sarking and the insulation board was maintained by the fitting of small 50mm fillets.

Once the No More Nails had set and the insulation boards were secure, the 145mm insulation slabs were cut and fitted into the party wall partition.

So there we go, now you have information on the installation of insulation and an indication of it's initiation and inception. 

Party Like It's 1999 (2015 edition)

A Party wall is a main separating wall between buildings.  Responsibility for the wall is normally shared between the owners of the buildings (the parties).  In this case the Party wall is the wall which separates the two homes within this semi-detached building.

The last time i worked full-time as a joiner was 1999 and whilst the skills and techniques remain the same, the building regulations of 2015 have changed a wee bit.

The party wall was parged (coated in cement render) at the start of the year.

The building regulations require the construction of a 150mm x 50mm partition at the party wall.  This partition, like the oxter walls, will need to be insulated by the fitting of 145mm insulation batts and 40mm Kingspan/Celotex insulation board.  In the case of the party wall partition the 40mm insulation board is to be fitted on the back side of the partition and i've left space in the partition (the missing dwangs) for this to be slid into place later in the project.  It saves a £50 delivery charge if i make one large order of insulation with free delivery rather than 1 small and 1 large order.

One of the other changes in building regulations is that a minimum gap of 25mm must be kept between the back edge of the finished partition and the party wall to ensure adequate ventilation within the loft space around the whole 'box' of the conversion.  In this case the back edge of the partition will be the insulation board and the bare timber partition had to be built 65mm away from the wall to account for the 40mm insulation board.

The Party wall partition requires to be finished with two sheets of 12.5mm plasterboard which are then to be fully plastered, so overall the finished partition will be approx.. 220mm broad.  Hopefully that should provide adequate thermal and acoustic insulation between my neighbours and I. 

Heatseeker

Now that all the joists are in place it's time for the 1st round of insulation fitting

In the eaves, behind the steel beams, some of the original loft insulation was re-laid in between the joists.  Prior to re-laying I had to fit an eaves ventilation roll.  This is a corrugated plastic roll which ensures that there is a decent gap for airflow into and around the remaining loft space from the external eaves vents.

Sometimes people fit loft insulation and stuff it right into the eaves restricting air circulation and creating good conditions for condensation build up, fungal growth and potentially dry rot.  

I laid a second layer of insulation across the joists on top of the insulation laid between the joists to give at least a 300mm layer of insulation within the area of the loft which will not form part of the new room.  

One of the first jobs to be done way back at the start was to lift the existing insulation and i was surprised to find a layer of loose cork insulation under the original loft flooring.  A quick check on t'internet showed that loose cork had the same insulation qualities as approx 150mm of modern insulation quilt, so i set it aside and then when the time came I just poured it in between the joists of the floor of the new room before laying 100mm of insulation quilt on top. Not only will this provide good thermal insulation it should also improve acoustic insulation between the new room and the rooms below.