Roatan Insights © August 2001
News from the Honduras Bay Islands and North Coast
August 2001
By Pierre Renaldo, The Coastwatcher©

The Wheels of Progress

Last month I was telling you how impressed I was with the progress of the road building we are experiencing on Roatan. And just as suddenly as all those guys showed up, digging up everything, making big piles of dirt and making driving almost impossible, they are gone.

Vanished! They turned invisible in the blink of an eye, but the dirt piles and the rutted temporary bypasses are still with us. Some of those ruts are even challenging in four-wheel drive. I have to award the first prize to this road building company for showing total disdain and utter disregard and/or contempt for the public and road safety.

Maybe we will get a more efficient group after the election this fall. Or maybe we will just get more of the same with different faces. Isn't that the way it's supposed to work? Some new guy's brother-in-law will now be in charge.

Stupid is as Stupid Does

Hondutel has done it again. They have once more proven conclusively that they are not only the world's worst telephone company, but probably the world's most stupid too. They forgot to renew their contract with their internet computer systems provider and were shut off. I love it! This bunch of dummies got a taste of their own medicine, but it seems to make little difference to them. Just less work for everybody, so why worry about it.

The entire island was without any kind of telephone service for two days in late July. The central telephone exchange had a complete (nervous?) breakdown due to lack of maintenance over the years. The equipment they use is obsolete, discarded technology anyway, cast off by other telephone companies twenty year ago.

We still have rotary dialing, and dial telephones. Does anybody out there remember what a dial telephone looks like. I had to use one the other day. It sure was strange. I wasn't sure if I was doing it right but my call went through on the second attempt.

I have not used Hondutel as my Internet provider for many moons and now that we have local call access numbers with Globalnet (to get on the Internet) my phone bills have dropped 75%. Right! I said 75%. Imagine how Hondutel will miss those long distance revenues. They have held thousands of people on the island hostage to long distance charges for Internet access for many years, and now the ride is ended.

At this stage, we can only hope that this albatross becomes such a drain on an indebted government's resources that they will dump Hondutel just to get rid of the burden.

I would like to welcome the many new subscribers who joined the rapidly growing list of readers of "ROATAN INSIGHTS". I am getting ever positive feedback about the subject matter covered each month and that in addition to information about Roatan, the discussions about construction matters is of major interest.

Many of you have related to me plans to someday build on our island paradise and other neighboring islands and in the U.S. too. I have written a trilogy of books that will help you along your road to becoming one of the "informed" rather than remaining one of the baffled. You can preview these books at my Web Site: http://www.eroatan.com/cgi-bin/pierre.cgi?books

Beginning this month our construction discourse will center on two basic types of construction.

Concrete Block/Poured Concrete & Wood Frame Construction.

I will outline the process of each and let you draw your own conclusions as to which is most suitable to your needs, or more compatible to the unique characteristics of your project.

THE FOUNDATION

Before we move into this topic let me talk to you about concrete and some of its characteristics. This is one of the most common parts of almost any construction project and discussions about it can become very technical. I will try to keep it simple.

You may see some things on the foundation plan or the specs that you are not sure about. I will start with concrete strengths. You could run across this number: 3000 psi. This is the test strength of the concrete specified. Certain proportions of the ingredients used in the mixing of concrete will produce this test strength. It is not likely that there will be a weight of 3000 pounds per square inch exerted any place in the foundation of your house.

The number is derived from a test conducted on a cylinder of concrete 6" in diameter and 12" high. When an architect or engineer on a big construction project orders this test to be conducted, it involves several of these cylinders which are filled with the concrete being poured in some phase of that particular project.

Some cylinders are left at the construction site, and others are taken to a laboratory where the concrete test is to take place. Concrete gains strength as it ages. Usually it will reach the designated test strength in about 30 days or less, but tests are conducted on some of cylinders at earlier intervals.

Here's what happens. The concrete is removed from the metal cylinder and placed in a machine (press) that will exert enough weight on the concrete to cause it to break. The pounds per square inch or PSI number is derived from the amount of weight that causes that failure. If the machine registers 3,280 psi when the concrete fractures and it has cured for 30 days, then it has attained at least the test strength specified.

The reason that some cylinders are broken at earlier intervals is to catch problems early, especially in heavy construction. A test conducted in three days may result in a 2,000-pound break. That would indicate that the concrete was curing very quickly. Then another test, in seven days may break at 2,970 (pounds per square inch of surface of the test cylinder), indicating that the concrete was almost cured to the required test strength.

What strength concrete should you use in your house? I have only found it necessary to use 2500 psi and 3000 psi in residential work. If you want to waste your money on over-kill then that is your prerogative. But after being so diligent in getting cost effectiveness into all aspects of the plan that is possible, are you going to blow the savings on something nobody can see?

REINFORCING STEEL:

Q. If concrete is so strong, why does it need reinforcing steel?
A. Steel is used to give concrete other kinds of strength that are not inherent to its natural properties. If we make beams out of concrete, that have to span open spaces, we want it to have flexibility and tinsel strength, so it will flex and stretch without failing.

Concrete is most efficient in compression. By that I mean if a load is placed on top of a concrete structure that is adequately supported from below, that is the best use of the concrete.

Example. Your garage floor is most likely poured directly onto the earth. It is a ground supported slab, and your car tires transmit the (live) load onto the concrete slab. That is a compressive load, which is the most effective loading for concrete without any reinforcing or other support.

Reinforcing steel strengthens footing concrete so that the footings will be able to hold up greater weight than if there was no steel in them. The steel also transmits (spreads) these loads along the length of the footings keeping the concrete from separating, or breaking.

You may see some numbers on your foundation plan that looks like this:

4- #5 cont. This means that there will be 4 number 5 steel reinforcing bars running continuously through the footing, etc.

Number 5 steel is just like saying 5/8" diameter. If it were number 6 bars, they would be equal to
Six-eights or ¾". The bar number is equal to eights of an inch.

Example:
# 7 bar = 7/8". (There are decimal designations used for expressing bar sizes also, but they interpolate very closely to eighth inch increments. Using eights is easier to remember and less confusing to all.)

FOOTINGS:

As the word would suggest, footings are at the foot or bottom of the foundation. They consist of a mass of concrete and reinforcing steel in various widths and depths, depending what kind of weight (loading) will be placed on upon them.

Some other types of footings are call piers. They are used to support columns or concentrated loads and are sized according to how much weight they will have to support, forever.

That kind of weight, the kind that will be there as long as the building exists, is called the dead load. Those same structural elements that make up the dead load will have to support another kind of load. That is called the live load. This means the movable things that are placed in the building, something that can be taken out of the building as well. Furniture, appliances, clothing and personal possessions, etc.

CONCRETE BLOCK CONSTRUCTION:

Concrete Block Walls:

Masonry Units:

This is the traditional concrete block, very common in many types of construction. Your basement walls may be concrete block. Many houses have concrete block exterior walls. You may see the abbreviation M.U. on you foundation plan or floor plan. It means masonry unit, which is concrete block.

The most common size M.U. is referred to as 8"x8"x16". This is a nominal size. The actual size would be 7-5/8"x7-5/8"x15-5/8".

PRE-CAST CONCRETE LINTELS:

Lintels are concrete beams. Some are made in a factory (pre-fabricated) and are used to span openings in concrete block (masonry) walls such as widow and door openings. The pre-fabs also serve as a concrete form. The pre-cast lintel is partially hollow and fills up with concrete when the tie beams are poured.

TIE BEAMS:

This is a concrete structure that is formed and poured as part of a concrete block wall (in residential work) to strengthen the walls and tie them together. Sometimes it is formed as the final two courses (rows) of block at the top of the wall (poured in place). Another device similar to lintels is often used for the tie beam. It is called lintel block or 'U' block because it resembles that letter when the solid ends and middle web of the blocks are knocked out so that it will form a continuous beam when filled with concrete.

FILL CELLS:

The hollow openings in concrete blocks are referred to as cells or cavities. Some of them are filled with concrete and reinforced with steel to strengthen the concrete block walls.

PARGE COAT:

Concrete block walls built below grade usually have a thin coat of mortar cement applied to their exterior. After it becomes hardened, a waterproofing of some variety is sprayed or rolled over it, to help prevent leakage through the walls.

STUCCO OVER BLOCK:

Houses built with concrete block exterior walls frequently have stucco applied over the block to give the walls a smooth or textured finish. The stucco can then be painted with a good masonry paint to add style and color. Note: If you are not applying stucco to block walls and intend to paint them 'as is', I recommended you use a good block filler/primer before applying any finish paint. Consult your paint dealers for information as to the most effective products to use.

BASEMENT WALLS OF CONCRETE BLOCK:

One of the most common types of basement wall construction. Since basements are substantially below grade, and have the weight of the earth pressing against them, they should consist of something heavy and strong enough to withstand the pressure exerted on them from the surrounding earth.

I would suggest using a 12" concrete block in below grade applications since the added 4" of width will add to the strength of the walls. 12" block are a nominal 12" wide, 8" high and 16" long. The cells are larger and can accommodate more concrete and steel in each fill cell. Your architect or designer will specify the locations and numbers of filled cells and the size of the steel reinforcing to be used.

CRAWL SPACE WALLS OF CONCRETE:

In many areas of the country, poured concrete walls are the more traditional method of creating basements and crawl space walls. I do not advance any argument in favor of one over the other. It is a matter of cost and personal preference that determine what you use block or poured walls for your project.

STEM WALLS ON FOOTINGS:

These walls are concrete block built on top of a footing, but they do not extend to the vertical heights, as do basement walls. They occur below grade, in the finished construction. They can be from one to several courses (rows) high, but unlike a basement these walls will have earth in between them and then concrete (floating slab) will be poured on top of the earth and between and even with the top course (row) of blocks.

Now that is a mouth full. The next paragraph will enlighten.

STEM WALLS FOR CRAWL SPACE:

This is like a low headroom space under the house. It is called a crawl space because you usually have to crawl to get around in it. There is no dirt fill in between the block walls, and the floor of the crawl space may be crushed stone or roughly finished concrete. Then the floor built on top of the walls will most likely be wood frame construction.

MONOLITHIC SLAB:

As the word implies, something large and powerful that acts as a single unified force. The footing and the slab, together with any other related concrete structures required within the foundation are poured all at the same time, in one piece. This is not only one of the most cost effective foundations, but one of the most expedient methods of building a foundation as well.

This slab is designed to take the loading of whatever type walls you have specified. You can use concrete block, wood frame, steel or a combination of all three.

STRUCTURAL INTEGRITY:

Another major advantage of the monolithic slab is structural integrity. SOUNDNESS. Just as simple as that! One piece. The fewer joints, connections, splices, etc. the greater the structural integrity.

Structural integrity is the name of the game. When all parts of a structure are adequately tied together in the most effective manner, you have accomplished this most important aspect of soundness.

I have described what I consider to be the most common and practiced methods of building foundations in the preceding paragraphs. There are other more sophisticated foundations/slabs that are rarely used in residential work and while they are interesting, you are not likely to venture the extra money just to be different. You may even find a primitive method of providing footings if you looked closely at some old log cabin in a remote part of the woods and found the walls resting on wood timbers.

TO BE CONTINUED NEXT MONTH

Wood frame will be our subject in September, so hang in there and we will cover this very popular and important type of construction.

If you have questions please ask. Don't be embarrassed because you think your question(s) are/is silly. If you are going to build your dream home someday you will need to know the answers, so ask and avoid the pitfalls before it is too late.

Comments or questions?

Drop me a line:

Pierre

elouis@globalnet.hn

By Pierre Renaldo, Mountain Coastal S.A,. General Contractors, Construction Management and Construction Consultants.