Radon Mitigation Measures

Reduce Radon Levels

If you radon test exceeds 200 Bq/m3 for residential or 400 Bq/m3 in the workplace a second test should be conducted as confirmation before you embarking on any radon mitigation measures as levels can fluctuate If you first conducted a short-term test then now take a second long-term test. Alternatively, if you first conducted a long-term test take a second short-term test and if both tests are showing elevated radon levels you must now take action to mitigate radon to reduce the health risks to your family or employees.

Radon Reduction Techniques Work

Radon mitigation systems can reduce radon levels by up to 80%. The cost of implementing the radon mitigation measures depends on the size and design of the building. Grants may be available from some local authorities to offset the mitigation cost so please contact your local officer for advice on grants and mitigation.

What to Look for in a Radon Reduction System

In selecting a radon reduction method for your home or workplace, you and your contractor should consider several things, including: how high your initial radon level is, the costs of installation and system operation, your building size and your foundation type.

How a Radon Reduction System May Affect Your Building

In order to minimize the effect of installing a radon reduction system in your house or workplace, ask your contractor before any work starts how the system can be made to blend with its surroundings. For instance: radon vent pipes may be encased with materials that match the exterior of your house, or the pipes may be routed up through wall cavities.

Radon Reduction Techniques

There are several methods that a contractor can use to lower radon levels in your building. Some techniques prevent radon from entering your building while others reduce radon levels after it has entered. Alpha Lab generally recommends methods which prevent the entry of radon. Soil suction, for example, prevents radon from entering your home by drawing the radon from below the house and venting it through a pipe, or pipes, to the air above the house where it is quickly diluted.

Any information that you may have about the construction of your house could help your contractor choose the best system. Your contractor will perform a visual inspection of your house and design a system that considers specific features of your house. If this inspection fails to provide enough information, the contractor will need to perform diagnostic tests to help develop the best radon reduction system for your home. For instance, your contractor can use a "smoke gun" to find the source and direction of air movement. A contractor can learn air flow sources and directions by watching a small amount of smoke that he or she shot into holes, drains, sumps, or along cracks. The sources of air flow show possible radon routes.

Whether diagnostic tests are needed is decided by details specific to your building, such as the foundation design, what kind of material is under your house or workplace, and by the contractor's experience with similar buildings and similar radon test results.

Foundation Types

Your building type will affect the kind of radon reduction system that will work best. Houses are generally categorized according to their foundation design. For example: basement, slab-on-grade (concrete poured at ground level), or crawlspace (a shallow unfinished space under the first floor). Some buildings have more than one foundation design feature. For instance, it is common to have a basement under part of the building and to have a slab-on-grade or crawlspace under the rest of the building. In these situations a combination of radon reduction techniques may be needed to reduce radon levels to below the action level.

Basement and Slab-on-Grade Houses

In buildings that have a basement or a slab-on-grade foundation, radon is usually reduced by one of four types of soil suction: subslab suction, drain tile suction, sump hole suction, or block wall suction.

Active Subslab suction (also called subslab depressurisation) is the most common and usually the most reliable radon reduction method. Suction pipes are inserted through the floor slab into the crushed rock or soil underneath. They also may be inserted below the concrete slab from outside the house. The number and location of suction pipes that are needed depends on how easily air can move in the crushed rock or soil under the slab, and on the strength of the radon source. A contractor usually gets this information from visual inspection, from diagnostic tests, and/or from experience. Acting like a vacuum cleaner, a fan connected to the pipes draws the radon gas from below the house and then releases it into the outdoor air. Passive subslab suction is the same as active subslab suction except it relies on air currents instead of a fan to draw radon up from below the house. Passive subslab suction is generally not as effective in reducing high radon levels as active subslab suction.

Some buildings have drain tiles to direct water away from the foundations. Suction on these drain tiles is often effective in reducing radon levels if the drain tiles form a complete loop around the foundation.

One variation of subslab and drain tile suction is sump hole suction. Often, when a house with a basement has a sump pump to remove unwanted water, the sump can be capped so that it can continue to drain water and serve as the location for a radon suction pipe.

Block wall suction can be used in basement houses with hollow block foundation walls. This method removes radon from the hollow spaces within the basement's concrete block wall. It is often used together with subslab suction.

Crawlspace Buildings

In houses with crawlspaces, radon levels can sometimes be lowered by ventilating the crawlspace passively (without the use of a fan) or actively (with the use of a fan). Crawlspace ventilation lowers indoor radon levels both by reducing the buildings suction on the soil and by diluting the radon beneath the building. Natural ventilation in a crawlspace is achieved by opening vents, or installing additional vents. Active ventilation uses a fan to blow air through the crawlspace instead of relying on natural air circulation. In colder climates, for either natural or active crawlspace ventilation, water pipes in the crawlspace need to be insulated against the cold.

Another effective method to reduce radon levels in crawl space buildings involves covering the earth floor with a heavy plastic sheet. A vent pipe and fan are used to draw the radon from under the sheet and vent it to the outdoors. This form of soil suction is called sub membrane depressurization.

Other Types of Radon Reduction Methods

Other radon reduction techniques that can be used in any type of house include: sealing, house pressurization, natural ventilation, and heat recovery ventilation. Most of these methods are considered to be either temporary measures, or only partial solutions to be used in combination with other measures.

Sealing cracks and other openings in the foundation is a basic part of most approaches to radon reduction. Sealing does two things, it limits the flow of radon into your home and it reduces the loss of conditioned air, thereby making other radon reduction techniques more effective and cost-efficient. AlphaLab does not recommend the use of sealing alone to reduce radon because, by itself, sealing has not been shown to lower radon levels significantly or consistently. Sealing techniques have proven very difficult to identify and sealing quite often only leads to new entry routes reopens old ones.

Maintaining Your Radon Reduction System

Similar to a heating boiler radon reduction systems will need some occasional maintenance. You should make sure the system is working correctly and test at least every two years to ensure radon levels are continuing to staying low and that your fan is still performing well.

Remember, the fan should NEVER be turned off; it must run continuously for the system to work correctly.

The filter in an HRV requires periodic cleaning and should be changed twice a year. Replacement filters for an HRV are easily changed and are priced between £5 and £15. Ask your contractor where filters can be purchased. Also, the vent that brings fresh air in from the outside needs to be inspected for leaves and debris. The ventilator should be checked annually by a heating, ventilating, and air-conditioning professional to make sure the air flow remains properly balanced. HRVs used for radon control should run all the time.

Remodeling Your Building After Radon Levels Have Been Lowered

If you decide to make major structural changes to your building after you have had a radon reduction system installed (such as converting an unfinished basement area into living / working space), ask your radon contractor whether these changes could void any warranties. After you remodel, retest in the lowest lived-in area to make sure the construction did not reduce the effectiveness of the radon reduction system. If you are adding a new foundation for an addition to your building, address the radon problem during construction.

Buying / Selling

If you are selling a building that has a radon reduction system installed, inform potential buyers and supply them with information about your system's operation and maintenance. If your current radon test is over two years old conduct a new test on the building and include the report in your HIPs pack.

When considering buying a property with a radon reduction system already installed. ensure the test results are current, valid and below the governments action level. If the radon report is older than two years, conduct a new set of radon tests on the building before exchanging any contracts.

If you are buying a new build "located within a radon affected area" building regulations now require the installation of full or basic radon reduction features incorporated into the house / building. It's therefore very important to request a radon test be conducted to ensure the radon reduction features are working effectively and the results are indeed below the UK government's action levels.

How Can AlphaLab Help With Radon Mitigation ?

If you require advice on choosing a registered contractor for Radon mitigation or if you are a builder / DIY enthusiast and would like information on radon mitigation suppliers, we can provide you with a list of independently verified contractors.

For guidance on the instillation of radon mitigation systems and further information on the regulations governing new builds "located within a radon affected area" contact the Building Research Establishment (BRE) at www.bre.co.uk/radon

The publication "guidance on protective measures for new dwellings" is also available through the BRE's bookshop priced £30.00 (ISBN: 1860813283 )

Radon Mitigation Measures need not to be very expensive or intrusive so please don't ignore the problem or your family or employees health will be at risk.