House Extension Case Study - Janet & John

Janet & John (no, not from the children's books!) currently live somewhere in the East Midlands, in a 4 bedroomed detached house. They have 2 young children, John works full-time and Janet works part-time from home. Her office is the corner of the dining room at present, though she is quickly out growing this space. They ideally need an extra room downstairs.

"We need to move to a bigger house" said John one day. But when they looked at the price difference between their 4 bedroomed house and a similar sized house with a study it frightened them. An extra £40,000 would be needed to provide just this one small room downstairs, and also the houses of this style were not really in the area of town they wished to live.

How about Extending?

Janet suggested that they look into extending their house. They had a good sized garden, though they wouldn't need to take up too much space to accommodate a study. They would also gain from a larger kitchen - the extension would be 30ft by 8ft when finished. Janet contacted a local planner (an architectural technologist who had been recommended by a friend) who came around to have a chat. He made some good suggestions and came back a few days later with a quote for £750 for preparing the initial plans, submitting them to the council and then preparing and submitting the building regulations plans. This quote did not include the actual fees to the council which would add up to about £200. Janet arranged for another quote but that came out at £2000, so they went with the first quote.

Plans

The plans were drawn up and once checked by Janet and John, were submitted to the council. John was slightly concerned as there was two black drains where the extension was going to built. They were told that these could either be covered over with a special cover within the floor of the extension, or they could be moved. This latter option is the one they chose. Janet notified the neighbours of their plans as they would probably get letters from the council. After a few weeks a representative from the council came to look at the house and check the the plans were correct and that the extension would not affect any neighbours property. Planning Permission was given after about 7 weeks. Building Regulations plans were automatically submitted by the planner who would also send out requests for quotations to local recommended builders.

Getting the Quote

Fortunately a very reputable firm of builders had a cancellation at the time the Building Regulations were being submitted and they therefore agreed to take on Janet & John's project. They provided a quotation of £21,000 including VAT for the building work. This would be payable in 3 parts - first when DPC level was reached, second at plate level (before the roof is put on) and the last payment when all the work was complete. This was agreeable to Janet & John.

Building Work Starts

Work would start within the next 2 weeks. So, on a Wednesday morning in August at 8am builder arrived and immediately started work on demolishing part of the garden wall. This would allow for easy access for the mini digger and dumper trucks that would be needed for digging the foundations. By Friday, 2pm the foundation trench was completed and the first inspection by the council took place. Everything was Ok so the concrete was poured in. This would be allowed to dry over the weekend and the brickwork started on Monday. The new brickwork was to be "cut-in" to the existing wall to make it look less like an extension.

DPC (Damp Proof Course)

Enough bricks and brieze blocks were built up to go up to the DPC height. The plastic sheet was laid ready for the second inspection by the council. After this has occurred, more concrete was laid to make the base of the extension. It was now starting to look like a room. The first payment of a £7000 was paid to the builders. Bricking continued for the next week, until the roof height (plate level) had been reached. Janet & John were amazed at the speed of the building work, though there was 4 men working on the project all the time.

Roof

Watching the roof being added started to give the impression of a real building. The speed again was amazing, the whole roof being completed within 3 days. Spaces had been left for 2 extractor units as the cloakroom in the house was having it's window blocked up and also the size of the kitchen now warranted an extra extractor fan due to new building regulations on ventilation.

Windows and Doors

A window consultant came around and measured up for the doors and windows. Two patio type doors were being used and discussions were needed due to new regulations about the minimum size of door openings to allow for disabled access. It was decided that 2 double-opening french doors would be used. All these new windows and doors would have ventilation strips at the top, again due to building regulations. This regulation does not apply to replacement windows. There would be a two week wait whilst the windows were manufactured.

Knock Through

Once the windows were installed the extension section was now secure and the knock through of the kitchen wall could begin. An extra £80 had already been paid to a quantity surveyor for him to calculate the size of the RSJ beam that would be needed to replace the wall that was to knocked through.

It took a day for all the knocking down of the wall and inserting the RSJ to be complete, but when finished the size of the kitchen now started to become apparent. It's completed size would be 19ft by 11ft. There would now be major problems with using the kitchen as the sink was on the wall which was no longer there. However, the builders left the plumbing connected so that it could be used. Emptying the sink was interesting - it had to emptied down the cloakroom toilet - the outlet from the sink in there had been lost as soon as building work had started!

Plaster and Floor

The electrician came and positioned the new sockets for both rooms. He would need to return once the plastering was complete. It was now time for the plasterers to come in and do their job. The new ceilings in the kitchen and study were to be artexed to match the rest of the house. However, the artexer (sub-contractor) did not do a good job, so the builder arranged for the plasterer to come and re-do the ceiling, this time with plaster. Most ceilings these days are plastered rather than using artex. The floors to the kitchen and study were done, the one in the kitchen after the plumbing for the sink (which was moving into the extended part, was complete. Janet did not notice any disruption to the water supply even though the main cock-stop was moved, the old position would be right in the middle of the new kitchen floor.

Once all the new plaster was dry, it was time to start installing the new kitchen. The builders did this, though Janet and John had already assembled all the units. The kitchen was starting to look like a kitchen again, units going in, appliances being put in their new positions.

Finishing Touches

Once the plaster was completely dry - this took a few days, it changes colour as it dries - decorating could begin. Janet was advised that the first coat should be diluted 50% with water as the plaster tends to soak in what is put on top. Another two coats later and the study was finished. Next the kitchen. This was more difficult as Janet had to around the cupboards and also do the ceiling over the top of the cupboards. The use of a radiator roller was useful here. Tiling was done and then finally the flooring came in.

Overall Costs

The list of the costs involved with the extension for Janet & John was as follows:

Overall Opinion

Janet & John's requirement was to have a study. With the extension this objective was met and they also gained a larger kitchen. The overall cost came to just over £28,000 including the cost of the kitchen and flooring. This was good value for money compared to the minimum £50,000 that they would need to have found to move house to a property worth at least £40,000 more than their current property.

It was a good experience and overall took about 2 months to complete, including fitting a brand new kitchen.