Brian,
If you can do an addition to a house then you are way ahead of most engineers in the RP.
The typical house is designed by an engineer, drawn by a draftsman and built by a foreman. The engineer is likely the only one who has any basic understanding of strength of materials, compression and tension. He may be the only guy who can read well and is likely the only guy who can read a blueprint. Of course the engineer is not on the job site on a daily basis and may never show up. If you can afford to have one who will really be there or family members who really understand construction and can really supervise then you are extremely fortunate and you don’t need to read further.
The typical problems in the Philippines could fill a book. Most have to do with saving time and money. Some are cultural.
Here are a few problems:
“Do it the way we’ve always done it” mentality = Low standards. No lintels above windows (even in “good” construction). No grounding, undersized wires, over fused, no ground fault interrupters.
With the exception of the engineer, lack of basic understanding of the principals/theory of construction. No basic understanding of curing, tension, compression, chemistry, hydrology.
Foremen that are corrupt, steal, take a percentage from the crew, ignore safety don’t provide basic sanitation, cut corners and lie about what they did while you or the engineer were away. They get drunk and fight and go to jail. Saw this a lot.
Engineers that don’t understand engineering, project management what you want and will never show up on the job. They overcharge for materials and take a cut of the total project – an incentive for running up the cost. They bankrupt the project, blame the owner and move on the next victim.
Large crews that are fast and impossible to supervise.
Slowdowns, drawing out the work, milking the job for the pay.
Being blocked. If you are not on the highway, the road is blocked until you pay for an easement or buy the lot. If you are on the highway you get notice that you are blocking an easement and construction is halted. Maybe they pay off the engineer for a permit and a lot owner blocks them. Happens even to big contracts.
No permits. Guy I know had a fence built close to the shore and was given a “notice of illegal construction” by the municipality for no permit and violating the 20 meter shore easement (Water Code). He resolved it but was so disappointed in the process that he put the lot up for sale.
Pride and respect. Pride means I’ll never admit that I made a mistake, I’ll cover it up. Respect says I’ll never bring up a mistake by someone else. Never look ahead. Run out of materials in the middle of work. Run out of gas in the middle of a concrete mix. Ignoring problems and “just good enough”. Recognizing and voicing problems, and maintaining standards - not a cultural strength here.
Hollow blocks that fall apart in your hands. Not reinforced, no consolidating of concrete.
No drainfields. Single chamber septic system, poorly vented.
No perk test, no soil analysis for load bearing or drainage.
No sense of style.
Concrete problems in order:
Too much water - it makes the concrete easy to work, place, consolidate and finish. It also is a major factor in reducing strength. If the concrete is easy to place and consolidate then it is too wet. The amount of slump can be tested but you’ll know it when you see it after a few bags.
Too much rock and sand – a cheap mix ruins strength. A typical very strong mix is 1 bag cement, 2 bags sand and three bags of rock. I used this for columns and beams. 1-2-4 is ok for flatwork (floors). Typical local mix is 1-4-7 and lots of water.
Undersized rebar and not enough of it. Rebar is expensive. But it is the key to strength. There are online guides for rebar. You don’t need to be an engineer if you are patient and can read. Of course my rebar schedules were in the blueprints, were more than adequate and were easy to flow.
Poor aggregate - Crushed hard clean rock binds better than round, the size should not exceed ¾ of the distance between rebars. We washed all of the rock in my house. Almost unheard of in our small town.
I had very few of these problems. I built with local fishermen and farmers. I didn’t hire experts and barely had a foreman. I took a hands on approach.
I never mixed concrete until I started building my place in the Philippines. There are a lot of books, online guides and tips and I read many of them until I understood the concept. I watched it done on job sites.
For house construction, most concrete mixing is done in a “one bagger”. It mixes one bag of cement, rock, sand and water. The amount of rock, sand and water determines the strength of the concrete. I like to add a few gallons of water, add the sand and then the cement. This keeps the dust down. Then we add the rock and additional water until the slump looks right. Curing is a process of keeping the concrete damp for several days. This is important because concrete gains strength only if it has water available.
Concrete is very strong in compression but weak in tension. So rebar takes the tension forces.
I only let one of my guys mix the concrete. Everyone fed the mixer but he was the only one to add water. He counted the bags going in. This was a constant battle because his older brother always wanted to take over. It was almost impossible for him to tell his brother to back down. I always put his brother in charge of placing and consolidating. When the forms were removed, zero air pockets were a source of pride for him. So it helped him stay focused on his job of placing.
While hollow blocks make up the walls, the structural elements of the house (columns, beams and foundation) are all cast in place reinforced concrete. So you will have to learn the basics of concrete masonry anyway.
I used the cast in place method. We built our own forms and didn’t use hollow blocks. It costs more and is a little slower but there is no comparison in strength. My wife’s lot near the beach has real sloppy land and is prone to flooding. So concrete was the way to go for the first floor. Also, bugs can get inside the hollow block and find a path to the wood structure. Not in my house.
A draftsman did the coordination with an engineer that I never met. He drew the plans based on my drawings and had the engineer sign. They were complete with rebar schedules and diagrams. They were 500 pesos per sheet. The crew made 150-180 pesos a day and lived off site.
I started small, building the road and a large octagon bamboo tambayan. Then the CR, then a small 2 room house. By the time I started the main house we had a system. A small team of seven that knew what to expect and knew the standards. I was trained as well, knowing how to handle the project with complete confidence. It took 18 months to finish the job but I moved on site after only 5 months.
This is not the route for everyone but I had a lot of fun doing this. If you can read you don’t need to hire experts. They are generally the source of the problem not the solution.
Ted
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