Many homes only have a crawl space. Just as in ordinary cellars, can obviously moisture problems arise that carry negative consequences. Are you suffering from moisture or water in your crawl space? Find out here the possible causes and why it is best to solve this moisture problem as soon as possible.
How does water get into the crawl space?
Moisture or water in the crawl space is usually caused by groundwater that seeps into the crawl space through the walls or through the floor. Especially in autumn and winter, the ground becomes very moist, increasing the pressure of groundwater. If your crawl space is not sufficiently waterproof, the groundwater can simply wend its way in and you will obtain a layer of water in the crawl space.
But that's not all. Leaking or broken pipes can also cause water to enter your crawl space. In addition, poor or lack of ventilation amplifies moisture problems in your crawl space.
Is water in the crawl space bad?
Many basements and crawlspaces are sometimes flooded or have high humidity. This high humidity causes a large difference in vapour pressure between the crawl space and the living area. Through open connections such as shutters, meter boxes with pipe penetrations or connections between floors and walls, the moist air can enter the house. This can happen in three different ways:
- Vapour diffusion: water vapour moves from areas of high vapour concentration to areas of lower water vapour concentration.
- Capillary moisture transport: capillary pores are continuous, interconnected pores in, for example, cement brick with a size between about 10 and 1000 nm. In construction, capillary action occurs when water is soaked up by bricks (rising damp, rising damp).
- Air transport: an air flow from the crawl space to the house can occur if the crawl space has an open connection to the outside air, if there are air leaks between the crawl space and the house, or if there is a large pressure difference between the crawl space and the house.
As moisture seeps into the home, it can lead to a variety of negative consequences. Common consequences include:
- A musty smell in the house
- Mould
- Pests in the home
- Health problems, including shortness of breath, colds or (chronic) bronchitis
- Damage to your walls or floors, up to damage to the building structure
So it does matter if you are struggling with moisture or water in your crawl space. We strongly recommend having water in the crawl space thoroughly repaired treat.
What to do if there is moisture or water in the crawl space
There is no general solution for water in the crawl space. The best moisture solution to be implemented depends very much on the cause of the moisture problem. So always have a expert visit, as this person can accurately identify the cause of the water in the crawl space.
Usually, there are several options to combat dampness in the crawl space. To fix the problem permanently, it is highly recommended to hire a moisture expert. This will guarantee the best execution.
1. Ventilation
A damp crawl space should first of all be fitted with proper ventilation grilles so that condensation in the room has no chance.
Air leaks between the crawl space and the house should also be sealed if moisture problems appear. These air leaks exist due to several reasons:
- Routing pipes from basement to house
- Crawlspace hatches or cellar doors
- The capillary action of the house floor itself
Pressure differences between the basement area and the house must then be addressed. Vapour pressure differences can be created by three factors: the 'chimney effect' in winter (due to the temperature difference between indoors and outdoors), a mechanical extraction system that is not properly adjusted or wind pressure that creates underpressures and overpressures.
The basis is always: air that flows in through negative pressure must somehow also be able to flow back out. If the pressure difference cannot recover naturally, it must be balanced manually with the installation of, for example, a ventilation system.
2. Basement drainage
Is there significant groundwater pressure or significant amounts of water entering the crawl space? If so, you may want to consider draining the groundwater through a basement drainage. This involves pumping water out of the crawl space.
Do you suffer from moisture or water in your basement?
Then take contact with AquaConsult and our specialists will visit for a free moisture assessment, everywhere in Flanders & Walloon Brabant.
Frequently Asked Questions
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Frequently Asked Questions
A damp crawl space is usually caused by a high water table, poor ventilation, condensation or leaks. The most effective solutions to this are basement sealing or waterproofing, and basement drainage using a submersible pump system.
The most common causes of and solutions for a damp crawl space:
- High groundwater levels: groundwater remains pooled on the ground around your home, particularly during wet seasons. This damp problem is resolved by basement drainage using a submersible pump or a complete basement.
- Poor ventilation and condensation: this cause can be recognised by a musty smell, droplets on the joists in the crawl space and mould. This issue is resolved by adding extra mechanical ventilation.
- Leaks or penetrating moisture: this moisture problems cause localised damp patches and stains around the pipes in the crawl space. The moisture solution is waterproofing the façade or ensuring that the pipe penetrations are watertight.
A crawl space is often flooded after rain or is frequently damp because the rising groundwater seeps in through the porous cellar floor or walls. The rainwater builds up hydrostatic pressure against the crawl space’s foundations, causing damp to seek the path of least resistance.
When rainwater cannot drain away quickly enough into the ground around the crawl space, the local water table rises. This naturally has a number of consequences for your crawl space.
- Hydrostatic pressure: the groundwater presses against the concrete slab or the brick walls of the crawl space and seeps in through cracks, joints and porous brickwork.
- No waterproof barrier: older properties often lack a waterproof floor or wall finish in the crawl space that could serve as a waterproof barrier against rising groundwater.
- Poor drainage: excess rainwater around your home has no controlled means of draining away, as there is no basement drainage is present.
AquaConsult tip: Does water regularly pool in the crawl space after it has rained? If so, have our experts check your specific situation in good time, during a thorough damp survey, to prevent damage to wooden floor joists, rusting pipes and rising damp to prevent this from occurring in the rooms above.
Waterproofing a crawl space is carried out by means of basement, applying a waterproof cement coating to the floor and walls, or by installing basement drainage. The chosen moisture solution depends on the groundwater pressure and how the crawl space is used.
AquaConsult’s step-by-step guide to a sustainable, dry crawl space.
- Comprehensive damp survey: one of our experts will analyse the cause of the damp problem and assess the condition of the walls and floor of the crawl space.
- Preparatory repairs: any cracks, gaps or damaged pipe penetrations are first sealed watertight using injection resins before our experts can proceed with the effective damp-proofing solution.
- Installation of basement or -drainage: In basement waterproofing, several watertight layers of cement are applied to the floor and walls of the crawl space. In basement drainage, a dimpled membrane laid on the floor of the crawl space channels the water to a collection pit fitted with a submersible pump.
- Optimisation of ventilation: ventilation openings are provided for mechanical ventilation installed in the crawl space to maintain a constant level of humidity in the room.
The cost of installing basement drainage in a crawl space typically range from €1,500 to €4,500. The exact price depends on the area, the accessibility of the crawl space and the drainage technique chosen, such as perimeter drainage, floor drainage or a ground barrier with a dimpled membrane.
The main factors that determine the cost of installing a drainage system in a crawl space are:
- Type of drainage: the method you choose for carrying out basement drainage has a significant impact. Perimeter drainage along the walls of the crawl space is often more cost-effective than full floor drainage using a dimpled membrane across the entire surface.
- Size and working height: a low or hard-to-access crawl space requires more working hours and specialist tools to carry out the drainage work.
- Pump system: installing a high-quality submersible pump, including sensors and drainage pipes, is a key part of the investment.
- Floor finishing: the choice of additional floor sealing or insulation to prevent condensation is an additional investment.
AquaConsult will visit your premises free of charge to a thorough damp survey and a no-obligation, bespoke quote. Why not ask for one now? your free expertise to.
Yes, a lot of damp in the crawl space is harmful to both the house if your health. A crawl space that is constantly damp can lead to mould, wood rot in the floor joists, rusting pipes and a drastic reduction in the insulating performance of your floor in the crawl space.
Furthermore, the damp, musty smell rises into the living areas above. This creates an unhealthy indoor environment and increases the risk of allergies and respiratory problems. It also leads to high humidity at home until a higher energy bill, because humid indoor air requires much more energy to heat up.
You can prevent water from entering the crawl space by installing a professional cellar drainage system with an automatic submersible pump, combined with basement or a bottom seal.
For a swift and systematic moisture solution At AquaConsult, we follow these steps:
- Temporary pumping: water that has accidentally entered the crawl space can be pumped out immediately using a waste water pump or a submersible pump.
- Basement drainage: Where there is a persistent rise in the groundwater level, a dimpled membrane is installed on the floor and walls of the crawl space. This channels the groundwater in a controlled manner via built-in channels to a collection pit, from where a submersible pump automatically discharges it into the sewer system.
- Ground sealing and insulation: once the groundwater has been drained away, a waterproof ground membrane or insulation layer prevents ground moisture from evaporating back into the crawl space.
No, a crawl space should not normally be damp. Although slightly higher humidity is more common in unfinished spaces, such as crawl spaces, standing groundwater or constant moisture seepage is a clear indicator of a structural moisture problem.
A wet or damp crawl space almost always indicates that the groundwater level around your home is too high, the absence of a water barrier, damaged foundations or a faulty ventilation. Does the crawl space remain damp after rainfall or during wet seasons? If so, then a professional damp survey necessary to prevent further damage to the structure of your home.
You can ventilate the crawl space effectively by installing a sufficient number of ventilation grilles or ventilation ducts in the external walls of the crawl space, thereby creating a constant natural draught. At AquaConsult, we ensure optimal ventilation of the crawl space with our mechanical ventilation system. This system ensures active ventilation in your crawl space.
