The problems related with ‘Wet basements’ are manifold and the most frustrating ones. The walls and the flooring are affected the most due to wet basement. A proper understanding of the cause will help to fix the issue at an early stage and avoid laborious repairs. Through this article, we have made an attempt to share the most common solutions that basement experts advice under normal conditions –

 Maintaining the humidity level of rooms  between 30 % and 55 %

 A higher level of humidity will act as a catalyst for different kinds of virus, bacteria and mold. Dust mites gets dispersed quicker with the increase in the humidity level (above 50 %)

 A relatively low level of humidity will aggravate respiratory infections and skin allergies

Use Piggyback Solutions

If you undertake renovations like gutting the interiors and finishing the basement, utilize piggyback solutions for moisture based problems. Measures such as balanced ventilation system or vapor barriers/polyethylene air are economical and easier  to implement during construction.

Utilize Dehumidifiers Wisely

Summer days can be happy days by using proper dehumidifier systems in the basement. This helps to decrease condensation on floors and foundation walls. Exhaust fans are also a better option to decrease moist air from basement provided the  exterior replacement air is equally moist.

Measure  Relative Humidity

Removing excessive internal basement moisture via humidifier systems and ventilation are economical and simple. However, basement ventilation with humid and warm air is not the appropriate answer , if the problem  is condensation during summers. In such scenarios, ventilation through desiccant-type heat exchanger or an air conditioning system is highly recommended.

Dehumidification can be used to reduce odor and humidity in a basement, but cannot be considered as a permanent solution in highly moist basements.

As the air within basement dries, moisture gets drawn rapidly, causing more damage to interior finishes through spalling of concrete and efflorescence. After removing the sources of interior moisture, it is recommended to evaluate downspouts, gutters and surface grading around the house.

If all the attempts to fix basement moisture fails then proceed with an exterior or interior drainage system. First things first, so deal with the water problem by having an active sub-slab depressurization system, including washed-rock layer below this slab. This helps to draw moist air below the slab, decreases the moisture which enters home through slab openings. The best recommendation that an expert can offer is to seal and block any open connection to the soil outside the foundation and below the slab and sumps.

STEPS TO CONSIDER BEFORE IDENTIFYING THE RIGHT SOLUTION FOR BASEMENT MOISTURE PROBLEM:

1. Installing Correct Grading, Proper Gutters and Downspouts: - Many basement based water problems are solved by properly handling surface drainage and rainwater using downspouts and gutters with splash blocks or extenders to carry water away from the foundation. It is very important to slope the grade away from house. This must be done before installing the below grade drainage system, as above-grade corrections would help in solving the problem. If drainage systems are required, remove water at the source.

Exterior Drainage System: - Although Exterior drainage system is slightly costlier they are an effective approach for water control. It is costly because the installation calls for digging up areas around the foundation, the shrubs and other obstacles outside the house and rebuilding it similar to a new house installation. Place drain tiles on top or besides the footing with 12 inches coarse aggregate around drain tiles to enable future rectifications.

 Free draining board or membrane: - Drainage mats have become more popular when compared to hauling sand or pea rock to the site for backfilling purposes. It is not only cost effective but also permits placement against wall foundations  backfilled with any soil available on the site. Make sure to have a free-flow path to the below perforated drain pipe.

 Sump Draining: - Exterior drainage systems should open to the sump to pump the water out. Cover the sump with a childproof and airtight cover.

2. Drainage of interior channel above concrete slab: - In most cases, when water enters the basement, it is better to install the interior drainage system. The best approach is attach the drainage channel at the floor slab and base of the wall. By using another channel at the top of the slab, water can be collected and drained into the sump. It is then permitted to pass to the sump basin through a trap. Such systems are highly suited to concrete walls with cracks. This however does not solve the masonry wall problem as the water stays in the floor level block cores, and is lowered to the top portion of the slab. With this approach, the water isn’t completely removed from the space. This may create mildew, mold and humidity problems. It cannot drain groundwater from below floor slab.

3. Channel for Interior drainage within slab edge: - Yet another technique is to place the drainage channel at the wall’s base at the top of footing. It needs replacing and removal of concrete along the edge of the slab. The drainage channel then gets connected to drain pipe leading to the sump. The sump needs to have airtight cover. Such approaches are highly effective for those concrete masonry walls facing water related problems as it completely drains block cores. To permit drainage, the holes need to be drilled at every core base of the block. Based on the product installed, these systems have different prices and shapes. As moisture is permitted to penetrate block cores, it is important to place vapor-retarder coating on interior basement walls and cap the tops.

4. Interior system of drainage below slab: - Amongst the interior based drainage systems, the highly effective are the perforated drainage pipe, installed inside the footing perimeter. It needs replacement and concrete removal at slab edge. Placing drain pipe beneath the slab drains the region to the lower level. Just like an exterior system, this drainage pipe connects itself to the sump. This sump needs to have a childproof and airtight cover. For this approach, a critical component is the dimpled plastic sheeting placed beneath the slab edge at the base of the wall. Similar to a small egg crate, dimpled sheeting allows free wall drainage into drain pipe. Compared to many specialized drainage channel systems, it is less expensive. Unless there is an aggregate layer below the slab, this system cannot accept rising groundwater in low permeability soils.

“Keystone Basement Systems, Inc. is a foundation repair company. KBS is not, however, a engineering firm and should not be considered as such.”

Tags: Basic information, Informative, Overview

This entry was posted on Tuesday, November 3rd, 2009 at 12:37 pm and is filed under Advice, Basic Information, Remedial measures. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.