The size of a two storey extension will be dependent on its location and what type of planning permission you require. As described above the only location for a double storey extension on your house without the need for planning approval is on the rear. We have however worked with several clients that were looking to gain consent for a double storey extension on the front of the property. Making changes to the front of your home is one of the more difficult elements to gain planning approval for, the reason for this is the council is keen to preserve the character of an area so introducing a new element to the front of the house can easily look out of place. It is a lot easier if you live in a road where there is a range of house shapes and styles, if you do make changes to the front of the house you’re not going to make it look drastically different from the others in the road. The other driving factor with this location of extension is making sure the proposed design does not protrude considerably more than neighboring houses as the council like to maintain a consistent line of buildings. If you live on a road that has a staggered build line it is easier to get approval to bring the front line of your house further forward. An extension to the front of the house can allow for an enclosed porch to remove coats and shoes from your hallway, you may choose to extend the hallway into the new footprint to achieve an open space, this really helps to give a sense of arrival to a home. We have been in many extended three-bedroom homes, where extra bedrooms have been added but the hallway was not extended, the house can still feel like a tight, three bedroom home. At first floor level, the added space can allow for the small box room to be extended making a more useable room. The larger front bedroom can be extended forward allowing for an ensuite or dressing room to be built in the remaining space in the middle of the house. On larger properties a central extension can mean an additional bedroom can be created or the opportunity to create a gallery landing which adds height to your hallway and the opportunity to flood light into this space making it feel more welcoming and open.
There are no set dimensions you must work to for front extensions but remember to respect the character of the area and try and stay within the build line of other properties in your road as this will give you the greatest chance of gaining approval.
One of the more popular locations for a double storey extension is to the side of the house, if you extend to the front or rear it generally results in you building in front of a bedroom which means it is more difficult to add additional bedrooms. Extending to the side can be a great way to extend your third bedroom, increase the size of your family bathroom to allow for a large walk in shower or add additional bedrooms or a master suite. At ground floor level you can generally build up to your boundary but in most cases, you will have to set the side of the first-floor wall in by 1m from the boundary. When building extensions, it is more cost effective to have the ground and first floor wall aligned, if they do not you will need to install steel beams to support the upper floors which can add a considerable amount to the build cost. Most builder will be able to build a single storey extension at £1650 + VAT per sqm, if the first-floor walls lines up with the ground floor the cost of first floor would normally work out to around £1000 + VAT per sqm. If you need to start introducing steelwork and pitched roofs to cover the remaining extended ground floor footprint, the price per sqm for the first floor is likely to increase to £1200 + VAT. The amount of space that you have from the side of your house to the boundary is really going to dictate how you use the new space and what can be created. If you have around 3m to the boundary, by the time you set this in by 1m, allowing for the thickness of the new wall you are left with an internal space of 1700mm, this is around the width of the smaller bedroom on a three bedroom house. On houses with this distance to the boundary it can be better to extend the third bedroom into the extension, if the extension is the full depth of the property the space left over could be used to get a small fourth bedroom or to be used to add a family bathroom and turn the existing bathroom into an ensuite that is accessed via the rear bedroom. If you are fortunate enough to have 4m or more to the side of your house, then the space can be used to create a large master suite with an ensuite to the front and spacious bedroom to the rear of the extension. You can get a master suite to work in narrower extension but be careful with the width as you don’t want to complete the build to find you have to squeeze past a bed to get from one end of the room to another.
The ground floor space on a side extension can allow for a garage or storeroom, a ground floor toilet and utility room. If you are wanting to extend your existing kitchen, the side wall of the house can be removed and the kitchen extended into the new extension allowing for large bifolding doors to be installed on the rear and the larger footprint can then allow space for a central island or large breakfast bar. If you feel you do not need a garage then the front of these extensions can be turned into habitable space creating a spacious study or home office, they work really well for these types of rooms as you are able to create a space away from the kitchen area allowing for some peace and quiet if you need to make calls or concentrate on a piece of work. Equally the space could be used to create a playroom which not only means the toys can all be kept in one place, but you can have a clutter free living room again.