If you find out that your house needs a radon abatement system, it's understandable that you'd want to get bids from different radon mitigation contractors. Once those bids come in, it will be tempting to go with the lowest number, especially if the bids vary by several hundred dollars. After all, the typical radon reduction system is just a network of plastic pipe, connected to a fan that sucks radon gas from below the house and expels it outside. What explains the difference between high and low bids, and why is your system projected to cost more than the one your neighbor put in?
While it's true that the components and function of a radon mitigation system are pretty basic, there are a number of factors that can make one system more expensive than another. As with other home improvements, you often get what you pay for. Here's a brief summary of what an experienced radon mitigation specialist considers when designing a system.
- House size and design. As the area covered by the foundation increases, you can expect the cost of a radon system to increase as well. When a house has a basement that is connected to one or more crawl space foundations, this usually makes the radon system more complex and more expensive.
- Sub-slab soil conditions. Many building codes require concrete slabs to be poured over a base of compacted gravel, and this is a good thing for radon abatement. Air spaces throughout the gravel base provide good airflow, allowing a single penetration through the slab to exert radon-extracting suction over a broad area. If the slab was poured directly on dense, compacted soil, more slab penetrations will be necessary to achieve the same suction coverage.
- Existing foundation conditions. Cracks in foundation walls and floors can allow large amounts of radon gas to leak inside a foundation. The same is true for sump pits. To effectively extract radon gas from below the house, a contractor will need to seal most of these leakage points. It may be necessary to fit an airtight cover over a sump pit or install a new sump pump that comes with one. Since the same cracks that admit radon gas often admit water, some homeowners choose to combine waterproofing with radon mitigation. Although this adds to the expense, it's often a wise choice. In either case, sealing a leaky foundation adds to the expense of a radon system.
- Obstacles. An open, unfinished basement will make it easy for the contractor to install the plastic pipe that brings radon gas outside the house. When there are obstructions like finished partition walls, HVAC equipment and shelving or closet space, pipe installation will be more time-consuming and longer pipe runs may be necessary.
- Aesthetics. Will the pipe be exposed outside the house, mounted against an exterior wall? Perhaps the homeowner prefers to have an interior installation, keeping the pipe's exhaust stack concealed inside closets or chases, then exiting through the roof. An interior installation usually looks better, but will cost more because the contractor must run the pipe through finished parts of the house.