Designing a 2+ Storey House / Building

SOURCE
https://www.eng-tips.com/viewthread.cfm?qid=287466
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QUESTION

I recently graduated BS Civil Engineering – no work experience, but sadly I do not know how to design a 2 storey house manually.

Yeah the professors in our university thought how to compute beams, columns, footings, etc. individually - using our design codes in our country. But how do you design a whole building in the first place? Isn’t there a step by step way of doing it?

For example, analyzing the loads to be carried by the structure . . . then?

I really need your help, I feel like I’m lacking so much knowledge particularly in the field I decide to specialize in.

REPLIES

csd72
Yes you are not the first one in this situation. I got given two houses and was left to figure it out myself - I got completely lost but they expected me to.

Houses are actually the most complex things to design as they have every type of material and often complex load paths. Once you learn how to design a house then it is a really good foundation for larger things.

You only learnt about 10% of what you need to know at college and your learning curve is now going to be very steep. Ask lots of questions, but only once each and keep a notebook with all the things you have learned.

I will try and give you a process that, though it is aimed at houses, should be applicable to most buildings.

  1. Put down that pen/pencil and just have a look through the drawings for a half hour or so. Do you understand them? do they have enough information? How is the structure going to work for gravity and lateral loads (wind/earthquake). now pick that pencil up and write down these questions to ask the architect/senior engineer leaving space to write the answers. At this stage a comprehensive list of intelligent questions will make a good impression and avoid having to redo misunderstandings.

  2. Now first page will be a summary of loads, note live loads, calculate basic wind loads and any earthquake loads. Also note any areas that may have excessive dead loads - this may add to your list of questions (e.g tile thicknesses). Double check all your parameters and calculated loads before moving on to the next step.

  3. Now design the roof structure, if it is all similar loads and spans use one member size for the whole roof, otherwise use a maximum of 3 sizes for each type of member. Make sure that your dead loads allow for the weight of any roof coverings or ceilings and and services. Clearly note reactions as these will be used for walls and then foundations.

  4. repeat step 3 for floor members.

  5. now look at the walls for vertical and horizontal loads, design studs and cladding /bracing.

  6. now look at connections e.g tie down straps e.t.c and sketch the critical details.

  7. transfer loads down to ground and size foundations.

Focus on simplicity rather than pure material economy as this normally leads to the cheapest and least problematic build.

Keep timber sizes, grades and species to those that are readily available in your area. If you are going to do a lot of these then it is really worthwhile knowing what the cheapest structural timber is available so you can use this as much as possible.

Find out what typical local practice is and follow it unless there is a good reason to do otherwise.

Make sure that you get to see this building being built as nothing compares to the reality.

1 Like

Can you post *.pdf floor, roof and elevation plans so we have a better idea of what you are looking at? Do you have a geotech report?

Dik