Extensions

Our experience & knowledge allows us to help and advise at the planning stages of your house extension. We can recommend trusted Sheffield architects & structural engineers on your behalf.

We offer the full complement of trades which allows the extension to run smoothly and eliminates the stress of trying to obtain quotes from individual tradesmen.

We offer guaranteed start dates and realistic completition dates.
We pride ourselves on employing polite tradesmen who produce a first class finish.

Move or improve?

Moving house is widely considered one of the most stressful things you can do. Therefore if you are happy where you live in Sheffield and like your neighbours etc why not consider improving your existing home by building an extension. There are many reasons to extend your property including more space ie bigger kitchen, additional bedrooms & bathrooms, greater comfort and improved saleability or value. Careful consideration should be made at the design stage as a badly designed house extension may actually reduce the comfort or saleability and value. The first thing to do is identify the area available for the house extension. For example it is a bad idea to lose nearly your entire garden to build your new extension as this may actually make living in the property worse than before! Identify your exact needs for the new extension and any possible constraints such as location of public sewers, large trees, if your property is a listed building or situated in the green belt etc.

Once you have decided on the area available for your extension and the specification required it is advisable to appoint an architect. An experienced architect will be able to advise you of whether your needs from your new extension can be met and also if your proposed scheme is likely to be approved by your local planning department. One you have agreed a brief, your architect will produce some scaled drawings for you to see. At this stage do not be afraid to ask for amendments for anything you are not happy with as it is far easier and cheaper to alter things at this stage of the project rather than once work on site begins.

Steel work in a recent Sheffield house extension

On receiving a final scheme that you are happy with, a planning application will need to be made to your local sheffield planning department. All house extensions are subject to planning permission and building regulations. In simple terms planning permission relates to ‘what the proposed work will look like’ and building regulations cover ‘how it will be built’. Considerations might include – is the correct size steel work being used or is the insulation up to current standards etc. Once a planning application is submitted they usually guarantee to reply within 8 weeks, so once you have got your plans drawn up it is advisable to submit your application asap so not to hold up your project. Some of the things the planning department consider will be, are there any other similar projects already completed in the area, will the proposed work be in keeping with the area, will it reduce natural light to a neighbouring property, will it over look another property & they will also write to your neighbours to see if they have any objections. It may be that permission is granted subject to some conditions or amendments such as the extension can be done but only 1 window is permitted not 3 or the size of the windows must be reduced or the materials used to be altered due to appearance.

Once your project has been granted planning permission and has passed building regulations you can start your home extension! The first thing to do is clear the site of any foliage, the re sighting of any trees, creating access etc. Once this prep work is complete the digging of your foundations can start. It is advisable to dig a test hole to determine which foundation will suit your ground conditions best. There are many types of foundation. The traditional foundations used are a strip foundations. This essentially is a strip excavated where all load bearing walls are to be built. These are usually 600mm wide for domestic house extensions and are a minimum of 750mm deep but can end up being a lot deeper as concrete cannot be cast until ‘good ground’ is reached. If these trench foundations cannot reach good ground at a safe depth then piling will be used. This is where concrete piles are driven deep into the ground and then ground beams are cast across the top of all the foundation piles which in turn carries the load.  More recently raft foundations may be used. This a raft of concrete poured over the entire foot print of the extension. These usually incorporate several steel mesh reinforcing sheets. The advantage of raft foundations is that it spreads the weight more evenly, so often reduces the depth and therefore amount of excavation. Once you feel you have reached good ground you will need to get the building inspector out to sign off the foundation / footings. It may be that the inspector requests that the trench is made deeper. When digging foundations it is almost impossible to give a fixed price as you can never be sure exactly what the ground conditions will be like until digging begins, so therefore if anyone offers a fixed price for your foundations it is likely to be very high just to ensure they are well covered!

Cavity insulation boards

You are now ready to start building the masonry walls. Masonry walls are made up of two 100mm skins with a 100mm cavity (300mm total thickness). The cavity is then filled with insulation which may be rigid boards or full fill cavity insulation depending on the specification. The bricks and blocks are laid with a bed of sand and cement mortar mixed at a ratio of 4 parts sand to1 part cement. A plasticiser may be added in order to make the mix more workable. Wall ties should be added every 800mm and every third course of blocks. The specification of the masonry will be designed in order to get the desired load bearing capacity mixed with the thermal qualities needed. The outer skin (if bricks) will always be more decorative and will have to match the original house. However the the blocks used for the internal walls will vary depending on the spec ie light weight or thermalite blocks or concrete dense blocks etc. Lay your masonry up to Damp proof course (DPC). This is three courses above ground level. Concrete commons & concrete foundation blocks are used below DPC as they are better suited to the damp conditions. Once the masonry is up to DPC the cavity should be filled with concrete.  A damp proof membrane can then be added. The inner wall is taken a course of blocks higher to form a ‘tray. This allows any water that may get through the brickwork into the cavity to be forced out through weep holes on the masonry and keep the cavity dry. The building inspector will need to visit site to see the DPC prior to work carrying on.

When joining onto the original house there are two different methods. You can ‘tooth in’ the brick work or you can fix a wall starter to the existing wall. Toothing out is basically breaking out a brick every other course and inserting the new masonry so the brick bond is seamless. This looks a lot nicer but is a lot more time consuming and therefore increases labour costs.

First floor joists in a house extension

The masonry can now be built up to level for the 1st floor joists (if suspended floors are being used). In order to ensure that the new floor levels are seamless with the original a hole can be broken out in the existing masonry to see the top of the original joists and then levelled from this point. Once this is achieved the joists can be installed into pockets in the masonry. The masonry can then be built up to the next floor level (if double storey). Careful consideration should be made with regarding to the brick bond in relation to openings for windows & doors in order to prevent un-sightly changes in the brick bond or awkward cuts around these openings. Catnic lintels will be used to span these openings. The second set of floor joists will be installed as the 1st floor. The masonry can now be built up to the wall plate level.

The wall plate is usually a 4” x 3” timber bedded on with sand and cement mortar to the inner skin of masonry. This is then strapped down the inner face if masonry with large galvanised straps. This timber is used to fix the roof timbers to and usually for the ceiling joists to sit on.

Forming the roof

The roof structure can now be formed. Depending on the design of the existing roof & the new roof will depend on how they are joined together. For example if a hipped or gabled roof is to be extended the new roof can be formed keeping the entire original roof structure in place it is only necessary to remove the roof covering where the roofs meet to provide a seamless joint. One thing that should be considered is the condition of the original roof. If the original roof is in good condition then it will look nicer to use reclaimed tiles or slates for the new extension roof area rather than using new tiles on the new roof area that don’t match the weathered original roof covering. If however the original roof is in poor condition then re roofing the entire property should be considered. Sometimes when extending a hipped roof it may be that the tiles stripped off the original hip can be used for the front elevation of the new roof to keep the original look.  Reclaimed tiles are readily available for any shortages. The building inspector will need to see the roof structure once it is formed.

Finishing the roof covering. In this case - slate

Once the roof covering is finished it is time for the internal 1st fixes and finishes. This covers things like building of internal stud walls, central heating pipe work, hot & cold feeds, drainage, fitting of windows and doors frames, electrical points & lighting circuits. Once all these are in then the extension can be prepared for plastering. All ceilings will be boarded with plasterboard and the internal walls will be dry lined. This is the fixing of plasterboards to masonry using dry wall adhesive. The advantage of dry lining over traditional wet plastering is the reduced labour costs, improved speed and also the greatly reduced drying time. Once all the walls & ceilings are prepared your extension is ready for the finishing plaster skim coat.

The final thing to do now is the second fix. This covers the fitting of all internal finished such as doors, skirting boards, arcatraives, window boards, radiators sanitary ware, kitchens, tiling, socket & light switch front plates.