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Pouring Concrete In The Summer
When the summer heats up, we often begin looking for methods of keeping things cool while outdoors. Whether we are trying to cool our gardens, our structures, or ourselves, water is considered one of the most effective tools in this regard. But not all things will benefit from added water, even on a hot summer day.
Concrete is the most widely-used building material in the world. It is celebrated for its compressive strength, which is produced by a combination of the chemical reaction between cement and water, and the presence of aggregate within the mix. The ratio between these materials within a concrete mix can have great effects on the strength of the hardened product. In particular, excessive water can have extended adverse effects on the strength of new concrete as it hardens and cures, and therefore can compromise the integrity of the resulting concrete structure.
Because of the impact that water can have on concrete strength gain, engineers have closely studied and observed the relationship between water content and concrete compressive strength. The figure below (https://www.engineeringintro.com/concrete/concrete-strength/water-to-cement-ratio/) is a graph representing that relationship, which shows the reduction of fully-cured compressive strength as the water-cement ratio is increased. The water-cement (w/c) ratio is the value of weight of water divided by weight of cement in a concrete mix. During concrete placement, the w/c ratio increases when water is added to the mix without also adding more cement. As we can see from the graph, the proportion of water within a concrete mix plays an important role in allowing the hardened concrete to reach its design strength.
Each year, the hottest months of the summer bring plenty of concerns for new concrete, one of the primary items involving high temperatures (see our blog post, August 13, 2012). In an effort to keep a concrete mix temperature down, it is no real surprise that someone’s first instinct might be to add water. But there are other effective ways to cool concrete without compromising strength- so that we can save some water and help build stronger structures.
Removing Rust Stains
It’s hard to find a building today without concrete surfaces stained by rust. Rust stains can adversely transform the aesthetics of a beautiful building. How can rust stains be removed? Let’s find out!
Once rust staining has occurred, it is important to remove the stains without altering the color or finish texture of the concrete. Two techniques which can be implemented are dry methods (i.e. sandblasting, wire brushing, grinding, etc.) and wet methods (i.e. waterblasting, chemicals, etc.). If surface texture is not a priority, the dry methods can be a quick and cost-effective way to remove stains. If the final finish is important, as is commonly the case with architectural concrete, chemical treatments are recommended.
Mild stains usually can be removed with an oxalic acid or phosphoric acid solution, applied to a water saturated concrete surface. Deeper stains typically require a poultice, which absorbs the chemical solutions and then forms a paste over the stain. Older buildings require more attention with stain removal because the chemical treatments may remove other contaminants in the concrete, creating a lighter color than the adjacent concrete.
The rule of thumb when putting a cleaning solution on your stained carpet or clothes applies with concrete. Be sure to test different chemicals on small, inconspicuous areas to evaluate the treatment. Also, the longer you let a stain sit, the more difficult it is to remove, so seek help quickly when rust stains appear!
Off To A Good Start!
In order to get your next roofing project off to a good start, be it minor repair or total replacement, the following is a list of items to discuss with your contractor to help ensure both parties are on the same page prior to starting the work. Reviewing some of these key items prior to job start-up will help both parties understand what is expected and hopefully make the job go a little smoother.
1. Review scope of work with the contractor to make sure everyone understands what work will take place. Ask if possible change order items are anticipated and what the unit costs may be for additional work.
2. Understand what the contractor’s anticipated start and completion dates are for the entire job. Knowing the working hours and if weekend work will be allowed is also important
3. Identify storage, parking and work areas. Make sure the contractor understands his responsibility for keeping the areas clean and maintaining the security of his equipment and materials.
4. Make sure the contact person in the field as well, as the responsible person in the office, is identified in case problems arise. Have a list of all emergency numbers of key personnel prior to starting work.
5. Clarify whether the contractor will utilize certain facilities (such s water, electricity and/or restrooms) while working on the job.
6. Bonds, insurance certificates, building permits or any technical submittals should be obtained prior to starting work. The Contractor should be responsible for securing any state or local permits or inspections.
7. Inspect property and document any existing damage prior to starting work to help protect all parties.
8. Understand who is responsible for connection or disconnection of mechanical systems.
9. Find out what warranties will be given from the contractor and/or manufacturer.
To Caulk or Not to Caulk?
Applying caulk to stop leaks is not always a good thing. Sometimes it makes matters worse by trapping water in the building façade instead of letting it drain. 
Here are a few areas where NOT to caulk:
*Along window or door head lintels on brick facades – leads to advanced corrosion of the steel support and either rotated/deflected steel or cracked bricks.
*Soffit (ceiling) of elevated concrete slabs (i.e. balconies, parking garage slabs) – traps water in the concrete and accelerates corrosion of the embedded steel and deterioration of the concrete
*Over/covering window weep holes – prevents windows from draining properly
Planning For a Tenant Build-out?
When renovating your building or planning for a new tenant build-out, there are some code issues you might want to keep in mind.
Most jurisdictions require a percentage of construction cost be allocated to upgrading the accessible route to the altered space. Many times this involves modifying the existing restroom facilities. Some ways to do this are:
1. Adding grab bars to toilets stalls (vertical grabs are now required);
2. Increasing stall size by reducing fixture count. Be careful to maintain an adequate fixture count to support occupant load; and
3. In extreme cases it may be necessary to enlarge the restroom by moving the end wall and will affect adjacent areas.
Many times this requirement is overlooked and can lead to delays in building permit issuance and increase design costs. Let us know if you need any help planning for future projects. Architect on staff!
Installing Linoleum on Concrete Floors
Installing linoleum or similar covering directly on concrete floors can be problematic if there is moisture in the slab. This is especially a concern with on grade slabs where there may be moisture under the slab that can permeate upward. Linoleum and similar floor
coverings act as a barrier that can cause moisture to be trapped under the flooring. When this happens, the floor covering can unbond, warp and become a serious hazard.
Carpet covering will let moisture vapor pass through and normally are not a problem. Carpet can be a solution where other floor coverings are adversely affected by moisture.
If a linoleum or similar covering needs to be installed, it is important to understand and analyze the moisture present in and/or under the slab. Various types of moisture testing can be performed to help verify that the concrete is dry enough to allow the installation of an impermeable floor covering.
Levels of Building Studies
Engineering studies fall into a number of categories, from general condition surveys (such as reserve studies and pre-purchase inspections) to problem-solving investigations and forensic examinations. Within those categories, there are generally three (3) levels of need.
Preliminary StudyWood Deck Collapse
A heightened concern over residential wood deck failures has become prevalent with the recent collapses in the DC – Baltimore area and with the arrival of warm weather.
https://wtop.com/howard-county/2018/09/8-injured-after-deck-collapses-in-ellicott-city/slide/2/
Several hundred injuries occur each year due to deck collapses according to published statistics. So, this is not a new phenomenon. The Building Code and local jurisdictions have required special details for connecting decks to buildings for many years. Often a lack of flashing or poorly installed flashing is to blame as, over time, water infiltration can result in the decay of the wood framing hidden behind the siding to which the deck is attached. We have also seen decks connected improperly (too few fasteners, improperly spaced fasteners) or to wood framing that lacks sufficient strength. Proper flashing and adequate structure must be present to ensure a well secured deck for the long-term.
FEMA has published this detail in their Coastal Construction Handbook for many years, which shows a robust flashing system.
https://www.fema.gov/media-library-data/20130726-1537-20490-9609/fema499_5_2.pdf
Unfortunately, not all decks have not been installed with proper fasteners and flashings. So, we will likely continue to see these collapses from time to time in the news. Montgomery County, Maryland officials have provided this checklist for annual deck inspections of residential decks by homeowners.
https://www.montgomerycountymd.gov/DPS/Resources/Files/RCI/Deck-Maintenance.pdf
It is a good practice to make an annual inspection of your wood deck, especially if it is 15 or more years old.
Buying A Condo Part 3 – New Vs. Old
There’s something inherently appealing about buying something brand new, but newer isn’t always better, especially in construction. A dishearteningly large portion of our work involves problems in new buildings, ranging from shoddy workmanship to new technologies that don’t live up to expectations.
One advantage to buying a unit in an older building is history. Inherent or latent defects can take time to manifest and new structures are not time-tested. There are steps that can be taken to help determine the condition of a new building, the first of which is a professional transition or warranty study.
Most states (and The District of Columbia) have in effect statutes regulating the formation and governance of community associations (condominium acts) and they typically include provisions for the correction of construction defects by the developer. That amounts to a statutory warranty, which has nothing to do with other warranties that might be offered to buyers by the developer.
Each state sets the criteria as to what constitutes a warrantable defect but they generally include any condition that reduces stability or safety below acceptable levels, restricts the intended use of a building element and/or does not comply with standards acceptable within the involved industry. Warranty periods vary by jurisdiction, usually ranging between two to three years. The acts also define periods during which lawsuits could be filed (statutes of limitations) and some limit the time an association has to notify the developer of any defects, often within the warranty period.
Before a warranty claim can be made, defects have to be identified and to the extent possible, quantified. That’s the primary purpose of a transition/warranty study. A secondary purpose can be determination of replacement reserve requirements.
Depending upon the age of the property, such a study could have been performed; however, it may not be made available to potential buyers. If the Association is embroiled in a legal action with the developer, reports might not (for strategic reasons) be made public during certain aspects of the process.
If you wish to buy into a new community and no such study has been undertaken, it would be in your best interest to propose, promote, or support one. In many cases, the burden of correcting constructions defects falls on the association if they weren’t identified within the time frames imposed by statute. Consumer protection laws in some states provide protection apart from and in addition to condominium acts, but even then, early is better.
The intent of this series is not to dissuade you from buying a condominium. All systems age and must undergo periodic repair, rehabilitation, or replacement. As long as the association has properly planned for those, the related issues amount more to inconvenience than hardship. If plans are lacking, you could be faced with having to pay for things that weren’t your fault, in the form of a special assessment or elevated assessments to pay off a loan.
Buying a Condo – Part 2 / Document Review
Buying a home in a condominium differs in a number of significant ways from buying one in an independent “neighborhood.” Condominiums (in fact all community associations) have by-laws, covenants, and budgets, to which you will be bound as an owner.
Governing Documents
An examination of the associations’ documents (especially the budget) is essential. Operations are obviously funded by unit owners and your share could be considerable. Monthly assessments can approach, or even exceed mortgage payments.
Reserve Studies
A reserve study should have been performed within the last three to five years and they should have been provided as part of the sale packet given by the seller. If not, be wary. In some jurisdictions (such as The Commonwealth of Virginia) they are mandated for specific intervals. The Federal Housing Administration (FHA) requires reserve studies every two years for certification and they won’t underwrite loans for first-time buyers in uncertified associations.
Reserve studies can be difficult to interpret for the uninitiated. Nonetheless, there are things to look for.
- Reserve studies should be performed by qualified organizations, based on engineering or architectural criteria. Reports with discussion of the involved elements are preferred over simple tables.
- Most community associations fund by the “cash-flow” method, which should cover a minimum of twenty years.
- There’s no simple formula for funding reserves, but lenders have tightened requirements and may deny a loan if annual funding is less than ten percent of the total operating budget. There should be some discussion from the author regarding the adequacy of reserves funding.
Engineering Studies
There may also have been engineering studies performed to evaluate specific systems and/or investigate problems. Disclosure laws usually require that they be provided to potential buyers.
There are differences, beyond the obvious, between older and new condominiums. In Part 3 to follow, we’ll go over some that should be considered.
Things To Look For When Buying A Condo-Part 1
Physical Inspection
When you buy a condominium you’re also buying into the building that encloses it, as well as every other building in the association and everything else intended for common (and limited common) use. You’ll be paying to operate, maintain, repair, and (when the time comes) replace them.
With that in mind, it would behoove you to inspect those elements. Detailed inspections are not practicable and space doesn’t allow for comprehensive discussions of every possible element or condition, but certain basic principles apply. In essence, if something doesn’t look right, it probably isn’t.
A simple walk through the property can be revealing. If the grounds are littered with construction materials (shingle remnants, siding, sheet metal, brick pieces, etc.) there’s reason for concern. If buildings exhibit bulges, missing cladding materials, excessive cracks, or other conditions that seem out of the ordinary, there are questions that need to be answered.
Parking garages with excessive and/or displaced cracks, exposed steel reinforcement or broken tendons (usually characterized by “cable” loops at the undersides of slabs) will probably require some degree of rehabilitation in the near future. Gutters in garages are almost always installed to collect water from leaks through defective waterproofing systems.
One thing buyers frequently fail to consider is noise. If you inspect the unit at a time when nobody is home in neighboring units, it could be misleadingly quiet. It might annoy your realtor, but try to arrange multiple (at least two) visits during hours when the neighbors are likely to be home and active.
While detailed inspections by prospective buyers are not usually possible, detailed professional inspections have likely been performed and reports would have been generated. In Part 2, to follow, we discuss documents you should review to help inform your decision.
Removing Rust Stains From Concrete
It’s hard to find a building today without concrete surfaces stained by rust. Rust stains can adversely transform the aesthetics of a beautiful building. How can rust stains be removed? Let’s find out!
Once rust staining has occurred, it is important to remove the stains without altering the color or finish texture of the concrete. Two techniques which can be implemented are dry methods (i.e. sandblasting, wire brushing, grinding, etc.) and wet methods (i.e. waterblasting, chemicals, etc.). If surface texture is not a priority, the dry methods can be a quick and cost-effective way to remove stains. If the final finish is important, as is commonly the case with architectural concrete, chemical treatments are recommended.
Mild stains usually can be removed with an oxalic acid or phosphoric acid solution, applied to a water saturated concrete surface. Deeper stains typically require a poultice, which absorbs the chemical solutions and then forms a paste over the stain. Older buildings require more attention with stain removal because the chemical treatments may remove other contaminants in the concrete, creating a lighter color than the adjacent concrete.
The rule of thumb when putting a cleaning solution on your stained carpet or clothes applies with concrete. Be sure to test different chemicals on small, inconspicuous areas to evaluate the treatment. Also, the longer you let a stain sit, the more difficult it is to remove, so seek help quickly when rust stains appear!