Pre Foundation Work

Most of this work is anything that needs to be put in under the foundation or is necessary for the foundation to be successful.  Things that need to be considered are utilities and soil.  As part of the utilities, considerations must be made for plumbing/sewer, electrical, media, and fresh water.  Inside of the soil question will be things like stability and draining.  If you don’t plan ahead for these factors then you will potentially be having to retrofit all or some of this and that will cause more cost in the long run.  It is nearly always cheaper to prebuild than post-build.

Let us cover utilities first.  Plumbing, this is water in and water/sewer out.  I broke down ‘fresh water in’ as a different category because there are special considerations with it, so let’s just cover outgoing first.  When you are talking about sewer you are talking about a gravity system.  The beauty of a gravity system is that it does not take external influence (electric, various engines).  One of the big downsides is you have to play with in the physics of gravity or you get toasted.  For example, gravity does not push up.  If you are planning on having your sewer running to a ‘tower’ then you will have to put your building higher than the tower, or pump it up to the tower.  A good example of this is basements.  If you have a basement usually you are going to need to pump the sewer stuffs up and out of the house.  Now not only does gravity make things go down, but many people in first-world countries also pipe that stuff to a desired location, instead of just making a drop hole exactly where they want it to fall.  If you are a piper then you have to add things like friction into the calculation.  The good news is, that you are not going to need to come up with the math to prove all this, usually, it is already done.  Thank goodness, could you imagine trying to find out the flow needed for water vs the big turd you just flushed down.  Talk about a big pain in the butt.  Ok, I’m done…Anyhow, the slope needed usually will be ¼ – ⅜ of an inch per foot.  That nasty math thing again, didn’t you do all the math you would ever have to in high school, yeah well if you are building your own house then get used to using it a lot. An easy way to do this, take your level and attach a piece of (whatever) to the end based on the length of your level.  If it is a one-foot level add ¼”-⅜” length extra height to one end.  Always make sure that end is on the ‘downhill’ side as you go along.  We have a 4-foot level for these long runs, which means ¼ x 4.  That makes a 1-inch (1”) drop for each check, when the bubble says level, the pipe is going down at the right amount. We just tied a piece of PVC pipe onto one end, easy and repeatable later if needed.  The reason it needs to be at the right amount is because water and solids have different friction amounts and therefore different flow rates.  If the water moves too fast it will leave the solids behind, as in the pipe (stoping anything else from going down, not pretty, 0 stars – do not recommend).  You need water to push stuff down the hill, so you need a slope but not too much slope so the water does not outrun the other stuff.

Another consideration in this design.  Air.  Air can push down or push up.  If it pushes down then it can help your water out.  If it is pushing up then water and air will be at a standstill until one or the other overpowers the other.  Of course, if you have a standstill with water then your solids also stand still.  One of the big problems is the solids are likely to not get moving again.  The other problem is the noise this creates.  Have you ever had a jug of anything (soda, milk, fuel) and been pouring it in such a way the air can’t come in except in the same hole the liquid is going out?  Every so often the air wins and pushes the liquid out of the way to get inside the container and ‘glub glub’ goes the operation.  Yeah, that will happen in your pipes every time you use them unless you have air flowing in from another hole.  If you look at most houses in the USA they have pipes on the roofs sticking out.  Those are ‘air in’ pipes, and prevent these two problems by giving the sewer system a way to have air ‘pushing’ down instead of up.

As a quick side note;  in many places in the world there are building codes.  In many places these are laws, but really they are ways to overcome known problems.  If you are building in these places, then you have to follow the codes (ideally being problem-free from there).  If you do NOT live in these places then you do not have to follow these codes.  If you choose to not follow these codes and just straight up ignore them, you will pay for these known problems that you will have later (in fixing the problems).  If you have a different way to overcome the problem that is not written in the code and you implement it, then you will not be up to code, but you will have solved the problem.  If you are overcoming the problem in a non-tested experimental way, then it is YOUR risk.

One more consideration to put into the design.  Easy way to say this, don’t try and put 5lbs. of crap in a 2lbs. bag.  It is not going to work.  Apply this to plumbing sewer lines.  Each item that is using the sewer system is going to be adding a certain amount of waste to the line.  If your line is too small then there will not be enough room for the additional amount.  It is great to have multiple things all tied into one line, but as more gets added you will need more space.  How much space, well you remember those codes?   They have already solved that math for you.  The codes have the answer to your specific inquiry.  Use those codes, if nothing else to overcome the known problems (like what size pipe you need).  The codes can help you design a system that will work even if you don’t use exactly what is written to overcome pre-known problems.  The codes are your friends and should be found (either online or on paper) and used.  Houses don’t cost $500,000 of material, they cost $30,000 ish of material and $470,000 of applied knowledge in skills.  You are going to pay either someone else to gain those knowledge and skills or you are going to pay (in time and money) for the knowledge and skills or you’re going to pay for it by fixing your lack thereof.

One more quick thing to cover is freezing.  Most people overcome this by putting the pipes in the ground at a depth that they won’t freeze.  This varies from location to location and you will need to know these numbers (codes again).  Where I currently live 20” will do it.  Where I was born in Alaska, 20” is enough distance for your pee to freeze before it hits the ground.  (small exaggeration but you get the point)  Both water out and water in lines will need to know this number.  You can also overcome this problem by adding heat to the lines.  Not only will you have to figure out how to add the heat to the lines you are also going to have to have a reliable heat storage idea, because if this goes down when it is cold, so does your water/sewer.  If you do go this route a bit of redundancy goes a long way.  It is way better than having to go out in the freezing to fix a problem or freezing with no water waiting for the other guy to come and fix the problem.  (never assume that things will forever go perfect and never break, because WHEN they do, you are going to get blindsided at the most inconvenient time).  For our particular house, it is designed more like a mini village.  This meant lots of piping underground that would go to each of the different buildings.  I have 12 people,  kids will grow up and move away in time, so being able to ‘shut down’ parts of the house, made this design work for us.  Most of our plumbing ended up outside in the ground whereas most people would have it inside the house and only have a small section of the whole system outside underground running to the end location (septic tank, city sewer pipes, etc.).  

Let us cover ‘water in’ lines considerations (besides freezing as covered in the paragraph above).  The source of water is a big consideration.  Running surface water (river, stream, etc.), Standing surface water (lake, pond, etc.), Bellow surface water (deep well, shallow well), or piped-in water (city water, rural water, etc.).  The biggest reasons you would want to know this are laws/codes, cleanliness of the source, and pressure of water. 

I have a hole in the ground, the expensive part, but that is it.  No set up to pull water up, or I have a pond that is spring-fed, or I have rural water.  I could go any of the mentioned routes.  Each has its own pros and cons as far as who does the maintenance, reliability, and sourcing (cleanliness).  Considerations must be made.  This is why lifestyle considerations must be put in.

If you live in a place that cleans and stores water so that there is ample pressure for everyone in the area, you are good.  If they are up, you are up.  Just tap into the existing system (the government imposing such codes/laws will probably need an official papered personnel to perform this, so if you are not then look into one).  If you’re getting your water from a surface source (because you have the water rights (again with the laws)) then you will most definitely have to clean it to drinking level somehow.  Now there are many commercial systems out there and each will target different items.  You will have to either know what you are fighting or you will have to ‘all things covered’ in the system.  Particles or sentiments will be a consideration (aka little bits of junk like rust or small rocks).  Biologic considerations  (it is not fun to drink your own death with bacteria/viruses/funges in your water) are other items to eliminate.  Another one is chemicals, we use chemicals to grow food here in the USA (among other uses).  If you think none of that ends up in the water then, either you are pulling an ostrich move or you are not thinking clearly.  You may not have all three in your water source, but you might and it is certainly better to know and fix it than to die from it.  If you are using under surface water then contamination is less likely, but only by a little.  Get your water checked or just assume it is and build in a filtration system. Please note that many locations, try as they might, still send dirty water to homes and even if you are hooked up to a government system, you still may be looking at cleaning your water.  

We are building a filtration system in our house.  I didn’t need to build the filter in pre-foundation but I did need to plan for this as pipe (that is pre-foundation) needed to be placed.  The freshwater pipes were placed properly to make a filter system a part of the whole house water system.  We have an already dug well that we are using, but other wells on the property have some contamination issues, so we are assuming this one does also and we are just going to filter it all out before it hits anything.   

The next consideration is the pressure of the system.  Now why do you need to know this before you place your foundation?  Well size and ability, do you need space for a filter system or storage system (water freezes easily remember).  Also, can the pipes that you are putting in the ground (to keep from freezing) handle the pressure of the source?  Now there are ways to reduce pressure, but if you don’t know you need to, hook up your system, blowing an underground or underhouse component, you will be kicking yourself for quite a while as you try and overcome that problem.  If you have the flip side and you don’t have enough pressure in the system then you can just plan on showering in a drip, or mister system.  Basically, if the water is not coming to you pressurized properly then you will need to properly pressurize it ‘in-house.’  Surface water people will most likely be tanking the water and need to pressurize it from there.  If you use underground water then you will most likely have a pressure tank involved with that setup and it will send water presurised to you.  If you have a government source of water then it is most likely coming from a pipe that is pre-pressurised and possibly over-pressurised for your system.  

The big reason we had to look at pressure is because our house is more like a mini village.  This meant lots of pipes underground that could become an easy problem if not properly planned for.  We put a 1” PEX pipe in the ground for our house.  Actually we have two water and sewer systems in our house.  The whole house would nearly never go down with this, only half the house at a time.  Many houses have a tank hot water heater and need to run two pipes to everything.  We are making each building have its own individual tankless hot water heater which made it so we only needed to run one pipe.  Additionally, again if one goes down I have many other hot shower or sink locations that could be used.  Finally, I didn’t have to insulate the pipes that are underground to keep them hot, just had to put them deep enough to not freeze.   

After it gets to the house then you have to get it inside.  If you are building the house ‘normal’ and have a fulling enclosed single structure, then you just need a single line of ample size going to the house.  If you are going to have multiple structures incorporated into the design then you will need water to each.  (One of the reasons this is before the foundation is because of the underground fix of freezing)  Make sure that the pipe does not get eaten up by your foundation.  (If you are not doing a pour foundation of any type then you are not going to need any of this pre-foundation stuff as you can run all these pipes after, but you may still find it easier beforehand).     

Now that your plumbing is in let’s talk media.  This might seem like an odd time to place this, but if you have to place this underground then it is easier to do now than after you have to place this under the foundation.  If you are building out of material that makes going in the side difficult (or ugly) then consider putting this in before the foundation.  Run all your ethernet cables and fiber optic cables you need now (and with proper conduit) in the same trench manner as the water.  Keep in mind that it will not freeze like water, so depth needs will not be the same, but straitness of lines is a good thing with fiber optic.  Note that if you do not need hard lines for security reasons in your house then just use WiFi.  It is much easier and less costly to install.

Some of you will need to put in an electric system through the ground.  If you need to do this, now is your time.  Much like your media cords (and can be run in the same trench more than likely) run these while keeping in mind that they will not freeze and can be run that way.  Also, these can be run in the air and you may not need to run them underground.  Please keep in mind depth (for future digging) and conduit (not a must every time but better to have and not need than need and not have).

Now the foundation for your foundation, the soil.  People are always saying that your foundation is the most important part of your house.  This is true mostly.  If you build an amazing foundation on something that erodes away, then it is not going to do you much good.  Basically you can’t think of the foundation as just pillars or concrete slab or such things.  Water will wash you away, wind will move you about, earthquakes will shack rattle and roll you.  The fact of the matter is, the earth is ever-changing and you need to be aware of those changes that frequent your area and build accordingly.  If you have a high-ground water location, a basement (aka digging deep) is a bad idea.

For most foundations, you will need to clear out the whole space under the house of topsoil.  Topsoil is great for plants because it is loose and easy to grow through.  Light and fluffy is not your friend when it comes to holding down your house and fighting against Mother Nature.  Get to the hard stuff.  The harder the better, most of the time.  The soil you are working with needs to drain off the water you get and needs to be a good anchor to your house.  Now you can modify your soil to match your needs.  You can reinforce your soil to make it stronger.  You can add drainage properties to make it drain faster.  You can level and unlevel.  Unfortunately, I can’t give you specifics because you haven’t given any to me.  Math equations can be easy to come by, but plugging data into the equation is a different matter entirely.

This can seem less than helpful, but I’ll give you the steps.  Step one.  Figure out what needs to be done to your soil.  Get your sold tested (or test it yourself).  Step two. Add things to the soil based on that information till the soil is correct (you may need to do nothing).

Now those two steps are the overly simplified version.  So questions you need to ask.  How much weight can your soil hold up? (you can spread the weight out but you need to know how much)  How much water can your soil handle? (this can be repelled or drained) Drain is usually better as eventually the soil will ‘leak’ and then hold the water.  How much shift will happen with this soil?  This is mostly a matter of compressibility.  What you are looking for is anchoring ability with this one, so the type of foundation will be a contributing factor on this one as far as how much you need.  If you have the answers to these questions (or can change your soil to be overkill) then you know what you need to build with.

Now that you have all the pre-piping in, media needs, electric needs, and the soil is ready it is time for foundation.