Building Confidence

Volume 18 Issue 11
ISSN 1923-7162

Welcome to Dave's Shop Talk's Home Improvement Newsletter of questions from our members on their construction projects, a Tip of the Month and a home remodeling article, both from our website at

What's New

Check out our new set of plans on our site for a queen size bed with drawers!

Tip of the Month

For exterior doors without sills and interior doors allow an extra 2" for the width and 2" for the height over the nominal size.

For bifold doors the finished opening is the size of the nominal size of door. Example: for a 30"x80" bifold, the finished opening is 30"x80".

KEEP BUSY! Now's a good time to catch up on your projects!

Ask Dave!

Dave, I think you mentioned a product that removes algae from brick or asphalt and it had three letters (maybe THS); you add bleach to it. You mentioned it in a tip-of-the-month not long ago. Thank you.

Yes, the product was TSP, tri-sodium-phosphate. This is a powder that you mix with hot water and scrub the surface. Read the label for the correct quantity/mix for the application. You can add a mixture of 1/2 cup of TSP and 3/4 cup bleach and 1/4 cup of Ultra Dawn in 2 gallons water. Mix well, pour on the area, let it set for 5-10 minutes, scrub with long handle deck brush. Wear gloves and keep off skin or in eyes. TSP is corrosive on tin and aluminum and plants, so watch the run-off when rinsing with the garden hose.


I am rebuilding a set of stairs down to the basement. The stringers and skirt boards are done and now I am ready to install one piece oak treads and painted risers. The skirt board is also to be painted. I plan to install the 3/4" risers with a finish nailer first and then cut each 1" tread to fit. I do not have access to the underside since the drywall has already been hung. How do you recommend attaching the treads? glue and finish nails? I want to avoid squeaks and want to limit any nail holes on the finished surface. Also, should I sand and put one coat of poly on both sides of the treads before installing and then put the final coat of poly on after installation?

I recommend using the construction adhesive in a tube for gluing the treads down. It fill voids and prevents squeaks. For 1" treads use a 2 1/2", minimum, galvanized finish nail or the same length finishing screw. I like these "finishing" screws. They are a small headed screw made of hardened steel, like a drywall screw, with a small, square, Robertson head. They are found at finishing stores, particularly stores that sell handrail parts and accessories.

If the basement is dry and heated, there is no need to coat the bottom side of the tread. Usually 3 light coats of urethane are applied for hardwood floors, including stair treads.


I want to reverse the swing of a door that is constantly in our way at work. It is a simple hollow core door (with window). I figure I should remove the trim from one side, work the jamb loose from the rough opening, turn it around, then reinstall the door in the rough opening. Is this best, or should I simply remove the door and hinges, chisel out for the hinges on the opposite side, and rehang it?

Hi Larry,

If it is just a matter of taking the jamb out and reversing it, leaving the door in the same place, remove the jamb. You should remove the casing on both sides. The casing is usually fastened to the jamb and the wall, both. It is easier to remove the jamb and flip it around rather than re-rabbet the hinges. I like to cut the nails or screws holding the jamb in place with a reciprocating saw with a metal blade. Notice if the casing has caulking around it. If so, cut around the caulking with a sharp utility knife. When pulling the finishing nails out of the casing, I find it better to pull the nails through the back side of the casing.

This doesn't leave a hole or chip the front of the casing. Checkout my article on hanging a pre-hung door, which maybe helpful. Remodeling 17: How to Install a Prehung Door


Hi Dave, Our toilet is leaking around the base of the toilet. Not much, but it's wet and gets wet right after we clean it up. Do you think it's the wax seal? If so, how do I change the wax seal of a toilet? Dan

Hi Dan,

Usually, the wax seal doesn't give a problem. I've never had to replace our seals since I built the house in 1992. That said, just the other day, we had to go to a client and replace their wax seal which was leaking. The only way to fix this problem is to lift the toilet. Purchase a toilet wax seal with flange. Don't buy the cheaper wax seal, only, or the wax seal with bolts combo, unless the original bolts were rusted or damaged, just the wax seal with flange built into it. This forces the toilet to drain directly into the floor drain.

Turn off the water supply to the tank, usually by the line stop on the left side of the toilet about 6" off the floor. Flush the toilet and remove the tank lid. Put it down somewhere out of the way where it won't get bumped or broken. Use a wet/dry vac, with paper filters removed, and suck the tank and bowl dry. Otherwise, use towels or rags to get the tank and bowl dry. Make sure no water is coming into the tank. If it is, the shut off is faulty and the main water shut off must be closed. (Replace the line stop, if it leaks, while the main water is turned off.) Remove the two brass nuts and washers and the plastic washers for attachment of the covers. Loosen the large plastic nut tight to the underside of the tank at the end of the supply tube. The nut may slide down the tube a bit. It should only be finger tight.

Grab the toilet under the rim and pull it off its mounts. Bring it forward, out of the way of the drain pipe and area where the toilet originally sat. You will need room to clean this area. Lay the toilet down, resting on the back of the tank and the toilet, so that the underside of the toilet is exposed. The next part is nasty, so get those disposable gloves on and have a plastic grocery bag handy. With a 1" putty knife or wooden paint stir stick, clean out all remains of the old wax seal around the lip of the toilet, as well as on top of the floor flange over the drain. If the seal had a flange built into it, remove this, as well. Put this nasty stuff into the plastic bag. Use comet and bleach or equivalent cleaner and wash the floor under where the toilet sat. If the seal was leaking for awhile, this area will be obvious. Also clean the outside rim of the underside of the toilet. Notice if there are any cracks under the bowl or wet spots indicating cracks.

Install the new wax seal under the toilet with the flange facing out. Push it in place hard enough for it to stay there, but don't mash it or change its shape. Remove the gloves and throw them in the plastic bag for disposal. Pick up the toilet, as before, and carefully place it over the 2 bolts. Make sure you can see the bolts coming through the slots of the toilet base. Also, make sure the supply tube and nut are lined up with the threads coming out of the bottom of the tank. Now put your hands on the top of the toilet rim, the cover and seat are in the raised position. Apply your body weight over the toilet forcing the wax seal to mash into place. Rock the toilet, slightly, back and forth until the toilet is down on the floor and no more vertical movement is felt. Line the tank up parallel to the wall and tighten up the large plastic nut to the tank, finger tight and replace the washers, on the base, as before. Usually the large plastic washer goes down first. Notice the printing embedded in the plastic, "this side up", or something similar. Over the plastic washer goes the oblong brass washer, then the nut. Tighten the nut finger tight, at first. Rock the toilet back and forth continually tightening the brass nuts on each side of the toilet base using a small wrench. Don't tighten these nuts too much for danger of breaking or cracking the porcelain base.

When the toilet doesn't have any rocking sensation stop the tightening. Maybe sit on it and see if there is any movement. These bolts are not there to crank the toilet hard to the floor, but just to prevent any movement. Now turn the stop on, opening it to the max so it won't leak through the shaft. The toilet should be filling with water, so watch for leaks from the supply tube, either end nuts. When the tank is full and the ballcock has shut off the water, check to make sure the water level is about 1" below the top of the overflow tube. Adjust the ball rod by bending it up or down slightly or adjusting the ballcock, itself, depending on the type. Flush the toilet, check the floor for leaks. If the toilet still leaks on the floor, your problem maybe a cracked bowl. This is rather rare, but it has happened to me before with a new toilet installation. You need to pull the toilet again and look under it to see if there are any leaks or wet spots showing. If all is well, check the water height inside the tank and replace the tank cover. Replace the bolt covers by snapping the covers on to the washers, pat yourself on the back and go have a shower.


Feature Article of the Month

(taken from our website:

Remodeling 1: Mold and What to Do About It

While answering a question from a member on the subject of mold in her home, I came upon this article written in March 2001 by the Workplace Safety and Health Division, Manitoba Department of Labour & Immigration, Canada. This article tells it all, so I want to share it with you. Keep in mind that this report is mainly for contamination in large commercial buildings; however, information contained in this report can be helpful if problems arise in your own home as well as the office.

Click here for a good vinyl siding cleaning solution that gets rid of mold, algae and mildew.

Introduction to Mold

What is Fungi or Mold

Fungi are primitive plants that lack chlorophyll and therefore must live as parasites or feed on organic matter that they digest externally and absorb. The true fungi include yeast, mold, mildew, rust, smut and mushrooms. They usually grow best in dark moist habitats, and are found wherever organic matter is available. Some fungi can grow under extremely difficult conditions. This section discusses those fungi known as molds (sometimes spelled moulds). Humid or damp conditions in the home, school or workplace may promote the growth of molds, as well as bacteria and dust mites.These organisms may contribute to poor indoor air quality and can cause health problems.

Fungi in indoor environments comprise microscopic yeasts and molds, known as micro fungi, while plaster and wood-rotting fungi are referred to as macro fungi because they produce sporing bodies that are visible to the naked eye. Apart from single-celled yeasts, fungi colonize surfaces as a network of filaments, and some produce numerous aerially dispersed spores and other chemical substances such as volatile organic compounds (VOC's). The naturally occurring substances produced by fungi that bring about a toxic response are called mycotoxins, and are usually contained in the spores. Toxicity can arise from inhalation or skin contact with toxigenic molds.

Health Effects

In most non-contaminated workplaces the possible mold exposure would not be expected to present a health hazard except to very susceptible individuals. In contaminated situations the risk from exposure to mold increases. Reactions are varied and complex depending upon many factors. Human factors include personal susceptibility, route of exposure, age and state of health. Mold related factors include amount and length of time of exposure, virility and viability of the organism, and whether the effect is infection, allergenic, toxigenic or some combination of these. The effects of inhaling mold spores include allergies, infection or irritation.

  • Allergic reactions - a significant portion of asthmatics are allergic to molds, so that exposure can bring on attacks. Other forms of immediate and delayed allergic responses, such as hayfever (allergic rhinitis), also may occur.
  • Toxic and Irritative effects - long-term exposure to molds has been associated with a number of non-specific respiratory and flu-like symptoms, headaches, skin problems and impaired immune functions as well as a lung condition in infants known as pulmonary haemosiderosis.
  • Infectious mechanisms - in immuno-compromised individuals, exposure to molds that would not normally cause illness can result in infection, termed mycosis. Under certain conditions, molds can pose a health hazard. Factors that increase the risk of illness include:
    • Susceptible individuals - those allergic to mold, those with low immunity and babies whose lungs are not completely formed.
    • High levels of exposure - exposure to large numbers of spores over a long period of time.
    • Species of mold - the more noxious molds (high potential for mycotoxin production) pose the greatest risks.

Not surprisingly, young babies, asthmatics, and persons who have poor immune systems (such as those undergoing cancer treatment and persons with HIV) are at the highest risk if they are exposed to large amounts of mold. However, although effects of molds on the general population are yet less well known, this does not suggest that mold growth indoors should be left alone. Mold in occupied buildings should always be kept to a minimum.

Molds of Health Concern

Indoor air contains spores and filaments of many different molds but the most common are likely to be species of Cladosporium alternaria and other mold typically also found in the normal outdoor environment. However in "sick buildings" one can find toxigenic or allergenic mold, including certain species of Penicillium, some Aspergillus, Stachybotrys and Fusarium. Most mold found in indoor air are able to obtain the nutrients they need from dead moist organic material. Wood, paper, surface coating such as paint, soft furnishings, soil in plant pots, and drywall can provide ample opportunity for mold to grow.

Investigating Potential Contamination

What triggers an investigation for mold contamination

An investigation for mold contamination can be triggered by adverse health concerns of occupants, observations of growing mold, unusual odours, or events of water intrusion. A variety of symptoms or observations, such as respiratory problems, headaches, nausea, irritation of eyes, nose, or throat, tiredness, fatigue, etc may trigger an investigation into potential mold contamination. Mold may be observed on walls, pipes, ceiling tiles, window ledges, books, files, documents, etc. Musty odours and other unusual smells may indicate potential mold contamination. Also, any indication of water intrusion, flooding, condensation or high humidity, especially if chronic and or severe suggests potential mold contamination. In most instances the precipitating factors for an investigation into mold contamination are a combination of occupant adverse health symptoms combined with a history of water intrusion. When mold is visible, maintenance or housekeeping staff normally clean it and remove it; i.e. visible mold is treated as "you see it, you get rid of it". Odours can arise from many sources, but in the absence of supporting evidence (e.g. occupant health complaints or an IAQ investigation that excludes other options) odours alone do not a trigger a mold investigation.

The building history

The mold investigator examines a building's history looking at the original design, original intended use, construction (materials, workmanship, location), and any renovations or additions. This information is examined for changes that point to potential opportunities for mold (or other biocontaminants) to colonize. Present use vs. the intended use When the present use of a building is different from the intended use, the original building design may not be suitable. For example, a basement area that was not intended for storage is often used to store old files and documents. Since the design did not intend the basement area to be ventilated and kept dry, when water enters or the humidity is elevated the conditions are perfect for mold to grow on these materials. Similarly, when a basement not intended for occupancy is converted to office space the occupancy of that basement can generate both high humidity and nutrient material for mold to grow. Another example, when office dividers and walls are erected and then occupancy is increased, the original HVAC system may be inadequate. Condensation and poor air circulation that results can lead to conditions for mold to grow. Probably the most significant change in building design to affect conditions fostering mold growth came from the demand over the past 25+ years for greater energy efficiency. This change resulted in many buildings having HVAC systems that were not designed to handle the excessive moisture that develops in these energy efficient buildings. The high humidity that results can lead to hidden mold growth in many parts of the building, and this growth is extremely hard to find because there may be no signs to indicate its presence.

Present state of construction or deterioration

As structures age they deteriorate; a building envelope begins to break down and if proper maintenance is not practiced the interior of the building becomes subject to intrusion of the elements, most notably water. When this occurs, biocontamination is likely to follow. An older building with apparent deterioration may require the services of a building engineer to conduct a thorough building envelope investigation. The results of this investigation can indicate where moisture may have entered and consequently where mold may grow.

The mold investigator should check the following:

    Building exterior:
  • Windows, doors, air conditioning units, dormers etc - is the paint peeling or blistering, is there rot or other damage that might allow water to penetrate.
  • Roof - is there damage that could allow water to leak in.
  • Exterior walls - are there breaks, cracks or other openings.
  • Joints at corners, top sills, side jambs, and where different claddings meet must be examined for continuous caulking that seals the joint properly.
  • Basement window wells must be examined for proper drainage (gravel and drain tube to base of wall is normal) and to be sure they don't leak.
  • Basement walls should be examined for cracks or other damage that could indicate water intrusion sites.
  • Drainage pipes (e.g. rain-trough down spouts) should be examined for damage or blockages that might lead to water entering the building.
  • Pipes that penetrate the basement wall (e.g. utilities) should be checked for proper seals.
  • Slope of ground around basement wall must provide proper drainage.
  • Drainage holes, pipes for water that might collect behind exterior veneer must not be blocked.
    Building interior:
  • Basements should be examined for renovations that might trap condensation, evidence of leaks around pipes that penetrate the wall, leaks around windows, condensation around cold spots or on plumbing pipes, plumbing leaks (water and sewage pipes, appliances), HVAC system, standing water (e.g. sewers, sumps, and puddles) active ventilation of the area, leaks from the floor above, relative humidity, materials that might sustain growth in high humidity, expansion joints at floor-wall junctions.

Present environment of building

A building's environment provides clues to potential mold contamination - usually these clues are water related. For example, high humidity, condensation around windows, in corners or on plumbing, stained ceiling tiles, blistered paint, peeling wallpaper, rotted wood around windows or near plumbing, mildew or mold in bathrooms, water stains around sinks (kitchens, lunchrooms, janitorial storage rooms, water in crawl spaces or basements, and leaks. Also, odour may indicate mold - many molds produce odours that are readily detectable. Activities in the building can contribute to mold growth; e.g. activities that generate moisture (fountains, showers, etc), accumulation of left over food, temperature below the dew point, and HVAC system that does not supply sufficient fresh air.

Impact of renovations or additions

Whenever an existing building is renovated or has a structure added, then opportunities occur for mold to grow. New components joined to old ones may not react to environmental changes in the same manner, and two structures may shift or settle separately. Components can work against each other causing separation and damage. When new internal structures are erected they can impede the HVAC system's ability to provide sufficient air supply or movement thus potentially creating conditions for mold to grow. There are certain kinds of mold contamination not readily detectable by the methods discussed in this report. If unexplained sick building syndrome symptoms persist, consideration should be given to collecting dust samples with a vacuum cleaner and having them analysed for fungal species. Recommendations have also been established for bulk samples of the inside of ventilation ducts.

Biocontamination Remediation Procedures


In all situations, the underlying cause of water accumulation must be rectified or fungal growth will reoccur. Remediation performed without first identifying and rectifying the cause of the biocontamination will result in a regrowth of the mold. Emphasis should be placed on ensuring proper repairs of the building infrastructure so that water damage and moisture buildup does not reoccur. Water infiltration should be stopped and cleaned immediately. An immediate response (generally within 24 to 48 hours) and thorough clean up, drying, and/or removal of water damaged materials will prevent or limit mold growth. If the source of water is elevated humidity, relative humidity should be maintained at levels below 40 - 60% to inhibit mold growth. It must be clearly understood that porous materials, such as furniture, ceiling tiles, plaster/lath, gypsum wallboard, similar building materials, and carpet, that have been become wet due to floods, roof leaks, sewage backup and groundwater infiltration should be discarded. Only in exceptional cases, and within 24 to 48 hours, should these materials be considered for drying and disinfecting. Special procedures are required for the restoration of books and paper. Professional conservators should be contacted for information on handling these types of wet products. The effectiveness of any remediation of contaminated porous material must be evaluated as a standard procedure in all abatement activities. Surface sampling is advisable on porous material adjacent to the removed contaminated material. All positive results in excess of background levels should be evaluated by a technically qualified person to determine whether additional remediation is warranted. The effectiveness of any remediation of contaminated building materials (plaster, drywall, roofing material, etc.) should also be performed. A follow-up evaluation should be performed in the remediation area after approximately three to six months to ensure that the growth of mold has not reoccurred. This follow-up evaluation may be air testing and/or surface testing, as appropriate.

Hiring a Consultant to Help

It is possible that, after evaluating the information in this document, you will not be able to resolve the situation by yourself. If this is the case, you will need to bring in some expertise to help you resolve your biocontamination problem. As there are no legal restrictions on who can offer their services as a biocontamination investigator, and it will be up to you to ensure that they are qualified to do the work before you hire them. The following is intended to assist you to find a qualified consultant.

Where Do You Look?

There are several sources one can check for information and the names of consultants available locally. Contacting professional associations and public service organizations related to occupational safety and health is a good place to start. These organizations include the Canadian Registration Board of Occupational Hygienists, the American Industrial Hygiene Association, and the Manitoba Association of Consulting Engineers. Another useful source can be the consultants listing in the Yellow Pages of your phone book. Finally, there may be a university, college, or hospital in your area that has an occupational or environmental health program. Their staff professionals are often available for consultation.

Defining the Work to Be Completed

Once you have found one or more consultants who can do the work, you will need to define the type of work to be completed. One of the best tools to accomplish this task is to have the consultants prepare a project proposal for your review. Often, in a larger job, proposals from several points of view are evaluated and used as one of the bases for the final selection of the consultant. In this case, answers to pertinent questions in the preceding section may be sought in the proposal rather than in the interview. Aside from background qualifications of the consultant, the proposal should answer the following questions:

a) How much is the service going to cost? Smaller jobs are often bid on an hourly basis, typically with a minimum of one-half day's work, plus direct expenses commonly specified. Larger jobs are usually bid at a fixed amount, based on the work steps described.

b) What is the consultant going to do? The answer to this question may range from a simple agreement to study the problem to a comprehensive step-by-step plan to solve it.

c) What will be the end result? The answer to this question is all too often not clearly understood; the result is usually a report that specifies the consultant's recommendation. If you do not want to pay for the preparation of a written report, and a verbal one will do, specify this in advance. As recommendations often call for construction to be carried out by others whose work is not subject to the consultant's control, results usually cannot be guaranteed. Rather, an estimate of the results to be attained is all that can be expected.

Thanks again to the Workplace Safety and Health Division, Manitoba Department of Labour & Immigration for such a thorough report. My following article, Moisture and Humidity Problems in the Home touches on some of these problems in the home and offers some solutions as well.

Almost the End

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Hi, I'm Dave Osborne. With over 50 years experience as a journeyman carpenter, foreman and contractor in heavy construction I enjoyed working with apprentices and sharing the tricks of the trade that others shared with me. Now I get emails from Members all over the world and we include many of my answers in our Free Monthly Newsletters. Some of my answers include drawings and instructions specific to a project, but may also answer your questions. I use correct construction terminology, so you can confidently inform your building supply dealers or contractors exactly what you need.


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