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Property Renovation Services – Start with the foundation…

September 17, 2018

We pride ourself in the high quality of property renovation services we offer. If you are about to start a property renovation project, whether its an extension or basement conversion, make sure your architect is on point with regards to the type and depth of foundation needed. Starting a property renovation project is daunting to say the least. As a homeowner, the question of “where to start?” is often overwhelming.

The SDA Build London team takes care of it all, from start to finish so that you don’t have to worry about the technical and regulatory requirements. Please do not hesitate to give us a call or e-mail us if you want any advice at all.

For a complete property renovation project, we usually start with the foundations. Various factors need to be considered including current foundation depths, soil composition and drainage systems amongst others. It’s key to get the foundation right when you are undertaking an extensive property renovation project. A foundation will not get passed by building control who will deem it unsafe for habitation if the latest building control regulations and standards are not adhered to. Before commencing full-blown excavations, we recommend that your builder digs a small area to assess current foundation depths. It is advisable to call your building control surveyor at this stage, who will be able to advise you on the depth and type of foundation you will require for your project.

Sourced from the Homebuilding & Renovation website, we found a handy guide on getting your foundation going.

What is a Soil Survey and Do I Need One?

A soil survey or investigation can help determine the type of foundations needed. This involves holes being dug at various points on the site and extrapolating the findings in each hole to assume the subsoil conditions throughout the site.

Soil investigations can prove very useful but are not a prerequisite. Most sites start without a formal soil investigation, relying instead on either the knowledge of the designer, or the local expertise of the building inspector.

What Type of Foundations Do I Need?

Simple Foundations

The standard routine is to place as little solid concrete as possible into trenches (minimum of 250mm) and then to build up from this in blockwork until ground level, where the walls switch to brick or stone or whatever the chosen external cladding should be.

This is known as a strip foundation (see image 3 below). A widely used alternative is to fill the trenches with ready-mix concrete to just below ground level (trenchfill, image 2) which saves labour but adds to foundation costs. Just above ground level, the footings are topped with a damp-proof course and then the ground floor is fixed.

Engineered Foundations

If the ground is deemed to be difficult, there are a number of options — all of them considerably more expensive than straightforward foundations.

The simplest solution is just to dig the foundation trenches deeper and then fill with a much greater depth of concrete, sometimes fitting sheets of polystyrene beside the trenches to act as a slip membrane.

However, there comes a depth (around 2.5m deep) beyond which it becomes impractical and dangerous to work, and the amount of concrete needed to fill the space becomes prohibitively expensive.

If the site requires deep foundations in more than a couple of spots, then it is now usual to use a different approach, most often piling, occasionally using concrete rafts.

Piled Foundations

Some housebuilders now use piled foundations on every site because the costs are predictable. Piles are driven into the ground and then filled with concrete, and the whole foundation gets topped with a ground beam to build off.

Raft Foundations

As the name suggests, a concrete raft  is designed to ‘float’ on the ground beneath. The structure is made up of an extra-thick floor slab, strengthened by masses on steel reinforcing. Rafts have the advantage of providing the base of a ground floor solution, not just wall trenching, but they are reckoned to be rather more complex to construct.

How Much Will My Foundations Cost?

Try as you might, the foundations are the one part of a building project that you cannot fully plan out until you start on site. Ground conditions vary and often problems only make themselves known when you break ground.

Costs will also vary depending on the foundation type you choose, with strip foundations being the least expensive.

It is also worth ensuring that you have a contingency budget available at this stage to be able to react to any unforeseen issues that may occur when you break ground.

How Do I Prepare the Site for Foundations?

A datum level must be set up for the eventual oversite level so that all trenches can be dug to accommodate that. On sloping ground, or with a design that employs differing oversite levels, that may mean that you should be prepared for shuttering with suitable 50x100mm timber.

You will typically need:

  • mesh reinforcement in the foundation concrete
  • compressible material for lining the trenches
  • a polythene slip membrane
  • cut metal pins to use as markers ready on site
  • several rakes and pairs of wellies (you’ll be surprised how many people turn up for work in trainers)
  • to be aware of any lead-in times. If the engineers have designed a foundation that requires reinforcement cages, these may have to be manufactured off site
  • to think ahead to getting the services into the house, so get some lengths of pipe or ducting to take through the concrete.

What Factors Can Affect Foundations?

Tree Roots

Where the foundations are affected by tree roots (or their previous removal), you may be required to employ a fairly deep trench filled with concrete but with a compressible material to one or both sides of the external trenches to counteract any heave or expansion in the ground.

Water Pipes

Water pipes must enter the building at a depth of at least 750mm but no more than 1.35m below ground. If that means that they pass through a concrete foundation then they must either be laid prior to pouring or, better still, a duct installed for them to be pushed through later.

Sewage Pipes

If sewage pipes leaving the building have to be deeper than the top of the foundation concrete then they should also be ducted; they cannot be trapped within the concrete and must be able to move freely.

Electricity and Gas

Electricity and gas don’t usually need to be ducted or installed at this point as they are normally surface mounted. Finally, the building and warranty inspectors will have to approve the excavated foundations prior to any concrete being poured.

The information above is technical in nature and usually it’s your architect, builder and building control surveyor who will manage these details. However, if it’s your home or a home that you are developing to sell, we believe it’s important for you to  have as much information as possible.

If you are thinking about a rebuild or a refurbishment of a property you own, why not get us around for a FREE, no obligation consultation. One of our experienced colleagues will visit your site, discuss your needs and give you our recommendations.

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SDA Build London, property renovation specialists, featured in Design Buy Build

September 14, 2018

As leading property renovation specialists in South West London, we are delighted to be featured in this month’s issue of Design Buy Build, one of the UK’s leading building publications.

The article showcases one of our favourite projects where we created a stylish, temperature-controlled wine cellar in the basement. Click here to read more… We are on page 14 at the bottom right.

We are specialists in basement conversions, restorations, loft conversions and extensions, so do give us a call on 0208 191 7595 or email us at enquiries@sdabuildlondon.co.uk if you are thinking about renovating a property.

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refurb renovation news showcases one of our favourite property renovation projects

August 18, 2018

Refurb Renovation News, the UK’s leading refurbishment title, has showcased one of our favourite property renovation projects in South West London. It all started with a subscription to a wine club. Read on to find out more ?

refurb renovation news

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Project Management Checklist

July 31, 2018

When embarking on a property renovation project, being organised and systematic is the first step towards ensuring a smooth process.

Whilst building your dream extension, basement or loft conversion is exciting and you want to start work with all guns blazing, it’s a good idea to slow things down and take your time in planning every little detail. You’ll be surprised about how many fine points you will need to consider.

We recommend starting the groundwork well in advance of when you want the building work to start. For many of our clients that means a year in advance give or take to obtain the necessary permissions, iron out any issues with neighbours and conduct in-depth research on builders, costs, kitchens, bathrooms, flooring, decking and all the nitty grittys of your property renovation project.

SDA Build London has created a FREE downloadable Project Management Checklist that might help you plan your project … step by step.

Ready to download

So, what are the aspects of a property renovation project that you need to consider?

The first step is to appoint an architect to create your plans and submit them to your council for planning permission. The architect is a vital member of your team as nothing can progress until the drawings and plans have been approved by the local council. It is advisable to choose a local architect who knows the rules and regulations of your area. If, for example, you live in a conservation area, planning regulations and restrictions will differ from those outside the conservation area. It’s usually the local architects who are aware of do’s and don’ts.

Planning permission approvals take 8 weeks from the date of submission, assuming there are no problems. If your plans need to be amended or your neighbour objects, this 8-week timeline might be stretched until the council, the neighbours and yourself are happy.

You will need a structural engineer to prepare detailed structural drawings so a builder can give you a quote. We’ve sometimes had clients ask us to quote based on planning permission drawings. Whilst we can provide very rough estimates with planning permission drawings, it’s impossible to prepare a detailed quote without structural drawings that tell us how much material we will need to complete your project.

You will also need building control permissions. Building controls are minimum standards for design, construction and alterations to almost every building. You will need to get building control approvals by applying via the Planning Portal. This is usually done or should be done by your architect prior to commencing work. Once you have given a Building Notice or submitted Full Plans, you can start work at any time, but you must give the Local Authority a Commencement Notice at least two clear days (not including the day on which you give notice and any Saturday, Sunday, Bank or public holiday) before doing so.

Do give us a call on 0208 191 7595 or drop us an email at enquiries@sdabuildlondon.co.uk if you’d like a FREE consultation on how we can help plan your renovation project.

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Property renovation almost complete? Now what?

July 23, 2018

Coming to the end of a home renovation is a time of mixed emotions – excitement, frustration, worry and, most of all, impatience to settle back in and have your home to yourself. However eager you are to get back to normal, though, the process will be smoother if you hold off a little. Follow these tips to make putting your home back together as seamless as possible.

Please click here to read the article on Houzz.

Give the SDA Build London team a call if you are thinking about a property renovation project. We’ll be happy to come around for a FREE consultation on what you can and should be doing to enhance your property’s value.  Call 0208 191 7595 or email us at enquiries@sdabuildlondon.co.uk to book an appointment.

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