Today's post is more informative than the usual juicy tale of Engineering Exploits. I'm often asked fairly esoteric information, such as 'how long does it take to drill a core in concrete'. Well, believe it or not, I typically do not witness this sort of thing. I request the test, and read the result, but I don't go out there and witness it. So, here I got the chance to witness the process. I carefully recorded the following answers to your burning questions about drilling cores.
How big is the apparatus? See above picture... It's that big.
How loud is it? You need earplugs if you are going to be within 20 feet, but it's not nearly so loud as a jackhammer.
What does the core look like? Well, kind of like a beer can made out of concrete. Until the lab cuts off the bottom, it's rough as shown in the picture. The driller actually drills the sides and then snaps off the bottom.
Finally, will the hole be patched? No, actually. The company that drills doesn't patch. If it needs to be patched for aesthetic reasons, then you need to call a concrete contractor.
Is it as smooth as it looks? Yes. The inside of the hole, and the outside of the core are smoother than wood grain.
And those, Ladies and Gentlemen, are the most common questions I get about cutting into the very heart of concrete structures.
Just to clarify: this isn't an invitation, really. It's more of just bragging of one of the cool things New Braunfels has to offer.
We all want trees around our home or commercial property. They provide shade and are interesting to look at. However, as far as your foundation is concerned, trees nearby are dangerous. For our case, nearby can be defined as: within 1 times the mature height of the tree.
Trees are giant sponges. As a tree grows and matures, it removes moisture from the soil around the roots. If the tree is mature, it has sucked all the water out of the soil contained in the root ball.
To put a foundation near an existing tree, we usually recommend cutting roots and installing a root barrier between the foundation and the tree. Often this is a grade beam several feet deeper than required by design. If the foundation is close to the tree, and many roots are cut, the tree may not survive. If the tree dies after you have built the foundation, then the moisture removal will stop and the soil will re-hydrate, causing swelling.
If you remove the tree and stump before construction, then the tree will stop sucking the water out of the soil. This means that the soil will re-hydrate and probably swell. This can be mitigated during construction by digging out the stump and moisture conditioning and compacting the soil that is used to fill the hole.
Some get around the whole situation by installing pier and beam foundations which are easier to re-level as the tree goes through it's life cycle.
Typically, the best solution depends on the size of your building and how closely construction will be monitored. Of course, how much you want that beautiful home wrecker counts, too!
Mr. Anon decided he wanted to build a deck on the back of his house. He went to the local home improvement store (LHIS) where he was given some advice about how to connect the deck to the house and also shown this nifty new product for the footing.
see how the 4x4 fits right into the hole on top? Perfect, right? Just needs a flat, level surface and you're halfway there.
But, no. See that advice from LHIS was free. And Mr. Anon had to rebuild the entire deck- including the attachment to the house.
1- the ledger attachment to the house is tightly controlled. For your edification, I posted below the part out of IRC 2015 for you to look at. As engineers, we are not about to go against such explicit building code.
2- things that are attached to the house are considered permanent. Permanent things need footers that are below the frost line or 18" deep minimum. You can see that this product does not meet that.
3- all load paths must be considered. As we all know, wind creates uplift, there is nothing in this product to keep the deck from blowing UP in a strong wind (then ripping off the house).
Now, I'm not saying that you all need to call me to add on a deck to your house. Actually, the City says you all need to call me, but that's beside the point.
The point is that home construction advice from LHIS is often worse than worthless. It is often damaging and costly to repair.
Also in the interests of saving you money and time and frustration (because I have your best interests at heart) the IRC has joist tables for minimum joist sizes for a particular span. It also has suggested details for a lot of typical connections on a deck.
Now that the heat of summer is waning, deck season is just getting started. Enjoy safely!
*Outlier totally gets the irony of giving out free advice while enumerating the shortfalls of someone else's free advice.