Jul 17, 2016   Tips    3,408
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What You Need to Know Before Extending Your House

Many of you may have a plan to extend your house for larger space and more functions to meet the lifestyle of the family. But if the extension is poorly planned, many annoying problems may follow, so we would like you to keep in mind these following points before starting to extend the house.

1. The Structure: You should consult with an engineer to make sure that the base and structure of the house can bear the weight of the extended part. It is possible that the extended part is too heavy or the structure of the house is not strong enough. You should take extreme cautions about this or else the house might be damaged or collapse eventually.

2. The Law: You must be obliged by the law to prevent the extension from being halted or the house demolished. What you need to be careful of when extending the house is the setback because the law does not allow you to extend the house to the edge of the land to prevent any negative effect on the nearby houses. The rules regarding the setback are as follows:
- An opaque wall with no vent and hole for light to pass through must have at least 50-centimetre setback
- A vented wall of a house that is no more than 9-metre high must have at least 2-metre setback. If the house is higher than 9-metre, the setback must be at least 3-metre.
- The balcony and veranda on the ground floor can be built to the edge of the land, those on the second floor must have at least 2-metre setback, and those on the third floor must have at least 3-metre setback. If you want them to have only 50-centimetre setback, you have to build an opaque baluster of 1.80-metre height along the balcony and the veranda. For the balcony and veranda on the second and the third floors which are extended from the house, they must have at least 50-centimetre setback.

According to Building Control Act in Thailand, extending a house is considered building modification which must always be allowed by the local the Local Authority before the process is begun. For more information, you can visit the Department of Public Work - Bangkok Metropolitan Administration's website at:

3: Plan: Prepare the plan in as much detail as possible to save time and cost for the extension. A detailed plan help you see the whole picture and so you can make some changes and buy all the materials needed at once before the real renovation is begun, instead of doing so during the renovation which can waste time and exceed the cost.

4. Cost: You should manage the cost of the extension based on the market price for the most accurate information. It is better to clearly specify the cost for each part such as the plan, the materials, the wage for the technicians and so on. You should also prepare some additional money in case the extension costs more than you expect because of the increased price of the materials, some changes in the plan during the renovation, or the delayed renovation, causing additional wages.

5. The Contractor: You should select a contractor that has a professional license to ensure that the work will be in line with the standard. The contractor should also have its own company and office where you can walk in and check the work progress and their responsibility easily in case any problem occurs. Do not forget to consider the contractor's previous work and credibility.
You should be cautious when making a contract by doing it in a written form and make sure it clearly states all the conditions and payment for the justice and the trust between both you and the contractor.

6. Materials: Select the type of material that meet your requirement the most based on the appearance, quality, property, durability, strength, and your budget. Do not buy the materials only because they are cheap as the low-quality materials can have a short useful life and cause accidents in the house.
For an extension on the upper floor, the materials used should be light so that the house does not have to bear too much weight. For example, you should use SHERA Board for a wall of a room on the upper floor instead of a brick wall which is heavy.

Just keep in mind those 6 points mentioned above from the start, and your house extension will be easy and smooth even if you are a beginner.
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