ChiefUserJaybeuu

Foundations for internal load bearing walls

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Hi

 

I'm a self builder in the UK and I got hold of the trial version of HB Pro to see whether it'll support the way we build houses here.  I've encountered quite a few difficulties and I suspect this will be the first of many posts and I hope the good folk on this forum will be able to help.

 

For reference I attach a pdf that shows the way that houses are typically built in the UK so you know where I'm coming from.

 

I have an internal load bearing wall that requires foundations.  In HD Pro I defined defaults for external walls, internal walls and foundations.  I drew the external and internal walls for floor 1 and the foundations were built for the external wall but no foundations for the internal wall.  I manually added foundations under the internal wall and aligned them, but the problem is that the internal wall and the foundations are not attached - the wall is built on top of the first floor and not directly on foundations.  See attached pics.  Can anyone pls advise how I can built the internal wall directly on its target foundation?

 

Note that I have tried defining the internal wall as a foundation wall but then I couldn't get the structure of the foundation to be the same as the foundations for the external wall (i.e. same depth of concrete fill, same height of stem wall).

 

Thx

 

Jon

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Typical UK Wall & Floor Structure.pdf

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Here in the USA no one is allowed to specifically design foundations except State licensed Structural Engineers. That said if you want to draw grade beams (foundation walls that support interior walls) you turn on the "reference floor display" so you can see the first floor walls in reference and then using the wall tool, draw in your required grade beams to support interior walls. It is simple and straight forward.

 

DJP

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You can drag the top and bottom of a wall up or down as needed, so you could fill in the gap either way.

 

In any case, this would be a good question for tech support.

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Thx for your feedback guys. After many hours of experimentation I’ve found 3 ways to do it using deep trench fill foundations.

 

Method 1: Select “Walls with footings” and “slab at top of stem wall’ in the foundations defaults.

 

Method 2: Do not select “slab at top of stem wall” in the foundation defaults but in the foundation wall structure select “Hang Floor Platform Above on Wall”” and “Subflooring to wall Interior”.  Then select for the ‘room’ that is bounded by the foundations that “Room Supplies Floor for the Room Above” and specify the floor structure to be concrete.  This allows me to place the concrete floor any between the top of the stem wall and the bottom of the footings.

 

Method 3: Use the same foundation defaults and foundation wall structure as method 2, but don’t select that the “foundation room” provides the floor for the room above.  In the room above specify for the floor as being concrete and it will place it at the top of the stem wall.

 

The attached pictures show methods 2 and 3.  Method 2 is the right hand side and method 3 is the left hand side.  I’ve set the floors at different heights to distinguish the two approaches.

 

It’s still not perfect because I actually want to place the first floor so that it overlaps the top of the stem wall and the bottom of the exterior and interior walls.  I’ve not found a way to do this as it appears to me the HD Pro defines wall heights of rooms by the position of the floor platforms that bound the rooms, and it doesn’t support floor placement that encroaches into the rooms that are above or below.  I actually want to be able to specify the wall heights and the position of the floor platforms independently, or change the composition of a wall part way up.  The other issue is that I want to specify more layers in the floor than the floor structures in HD Pro seem to allow.  I’ll might put these out as separate posts to see if anyone has any ideas.

 

Re grade beams, or “pile and beam” as I know them; they only tend to be used in the UK when there are difficult ground conditions.  The vast majority of houses are built using deep trench fill and it’s difficult to find local builders that know anything else.  All sorts of new foundation systems are being introduced but the take up is slow.   Some companies offer piled foundations with a reinforced concrete slab that is laid within a metal tray that is raised up from the piles so it’s suspended in the air, but such systems are expensive and the adoption rate is minuscule.  Another type of foundation used for difficult ground is “reinforced raft” where all the first floor walls of a house are laid on a thick reinforced concrete slab that ‘floats’ on the ground.  However, for ‘acceptable’ ground conditions, cost effectiveness, speed of build and an available labour force, deep trench fill is still the way to go.

 

Thx

 

Jon

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Off topic for your question here, but if your looking to see how HD Pro works for UK style construction generally, please have a look at windows and doors as well.  

 

There is a lack of inset control and the assumption that casing is the norm. It's possible to cover casing or gaps when using no casing with brick coloured soffits but placing them around every window and door is time consuming.  In my efforts to workaround lack of inset control which is a real problem for external/thicker walls and UK door/window placement, I changed my wall layers but then ended up with roof and wall joint issues so had to re-work the whole plan.  I considered using different wall types just for the door and window sections but's that just too much work and not without its own issues.  

 

I am a fan of HD Pro, but there are a some annoyances for non US style construction.

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