Hi!
I have just realized what type of house we actually live in and all that it entails for a major renovation. I must admit, I’m feeling a bit overwhelmed. We've always known it was a prefab house, but unfortunately knew less about its foundational construction.
We live in a 1 ½ story split-level house from -61. So far, we have done some minor renovations and encountered the panels and chipboard in the walls, and also confirmed that we have the typical “prefab floor structure” with panels between the living level and the split-level floor. In the split-level floor, which also serves as a basement, there is a customary supporting wall and some other walls. We are on bedrock and have no problems with moisture, sagging, or sinking floors (phew!).
Unfortunately, no original documents/plans are available, but based on all the fantastic information kindly distributed mainly in this forum, I have largely understood how the house is built. A huge thank you for that! Thanks to you, I have found extremely useful information about window replacement, bathroom renovation, and floor reinforcement, among other things. I intend to share as much information as possible through our planned major renovation, but I will start gently with a couple of questions I’m hoping some kind soul with knowledge of prefab houses and construction wants and can answer.
1. The Deck Challenge
Our living level is one floor up from the south side, which constitutes one of the house's gables. Therefore, we are planning to build a high deck here with an exit from the living level. The original plan was to attach the bearer beam to the wall/floor structure between the basement and the living level in the usual way, but now I've realized there is nothing to attach it to.
It is also not possible to attach the bearer beam to the split-level outer wall/masonry and allow the beams for the deck to rest on this, because the holes in the masonry for windows and doors are against the top edge of the wall. So, one would cover the windows and doors with a large plank, which is not feasible.
This leaves using some kind of vertical attachment to the wall, like posts, that go up above the wall, where the bearer beam can be attached. But there should be some buckling at the top of the post, outward from the house, which makes me unsure about the dimensions, number of posts, and whether this plan is even reasonable.
Anyone with tips/ideas? Please see the attached sketch of how I’ve thought, in principle.
2. Header Installation
One thing I don’t quite understand, despite all the info on the forum, is how to perform header installation at wall openings. We aren't planning to open too large, the largest opening being 2700 mm, but some kind of header installation is needed, and it must rest on something – posts. In our case, two 45x95s screwed together into a post will suffice, but what should they stand on? Can they be placed on the floor, or must they go down to the wall? It feels like the latter considering the house construction. If they are to go down to the wall, I’ll be making alterations to the “floor structure” as it is designed; how should I best secure it? And can I place the post directly on the wall, or does the load need to be distributed? How would one do that? Would you make a wider hole in the floor? Then you would further compromise the floor structure… How do you balance this? How have you others done it?
Please see the attached sketch for my thoughts.
Many thanks in advance to all the brave and patient prefab house renovators!
/J
I have just realized what type of house we actually live in and all that it entails for a major renovation. I must admit, I’m feeling a bit overwhelmed. We've always known it was a prefab house, but unfortunately knew less about its foundational construction.
We live in a 1 ½ story split-level house from -61. So far, we have done some minor renovations and encountered the panels and chipboard in the walls, and also confirmed that we have the typical “prefab floor structure” with panels between the living level and the split-level floor. In the split-level floor, which also serves as a basement, there is a customary supporting wall and some other walls. We are on bedrock and have no problems with moisture, sagging, or sinking floors (phew!).
Unfortunately, no original documents/plans are available, but based on all the fantastic information kindly distributed mainly in this forum, I have largely understood how the house is built. A huge thank you for that! Thanks to you, I have found extremely useful information about window replacement, bathroom renovation, and floor reinforcement, among other things. I intend to share as much information as possible through our planned major renovation, but I will start gently with a couple of questions I’m hoping some kind soul with knowledge of prefab houses and construction wants and can answer.
1. The Deck Challenge
Our living level is one floor up from the south side, which constitutes one of the house's gables. Therefore, we are planning to build a high deck here with an exit from the living level. The original plan was to attach the bearer beam to the wall/floor structure between the basement and the living level in the usual way, but now I've realized there is nothing to attach it to.
It is also not possible to attach the bearer beam to the split-level outer wall/masonry and allow the beams for the deck to rest on this, because the holes in the masonry for windows and doors are against the top edge of the wall. So, one would cover the windows and doors with a large plank, which is not feasible.
This leaves using some kind of vertical attachment to the wall, like posts, that go up above the wall, where the bearer beam can be attached. But there should be some buckling at the top of the post, outward from the house, which makes me unsure about the dimensions, number of posts, and whether this plan is even reasonable.
Anyone with tips/ideas? Please see the attached sketch of how I’ve thought, in principle.
2. Header Installation
One thing I don’t quite understand, despite all the info on the forum, is how to perform header installation at wall openings. We aren't planning to open too large, the largest opening being 2700 mm, but some kind of header installation is needed, and it must rest on something – posts. In our case, two 45x95s screwed together into a post will suffice, but what should they stand on? Can they be placed on the floor, or must they go down to the wall? It feels like the latter considering the house construction. If they are to go down to the wall, I’ll be making alterations to the “floor structure” as it is designed; how should I best secure it? And can I place the post directly on the wall, or does the load need to be distributed? How would one do that? Would you make a wider hole in the floor? Then you would further compromise the floor structure… How do you balance this? How have you others done it?
Please see the attached sketch for my thoughts.
Many thanks in advance to all the brave and patient prefab house renovators!
/J
Since you are fortunate to have bedrock as a foundation, the decking can be constructed independently of the house (posts + beams), making things much simpler. Take a photo of the gable to facilitate the possibilities for suggestions.
The loads on the posts that are to carry a load-bearing beam must somehow be transferred down to the heart wall. The posts do not necessarily have to stand on it, but must have a material under them that can withstand the load. If this material is a side beam in the floor cassette, the total shear force on this should probably be checked.
The loads on the posts that are to carry a load-bearing beam must somehow be transferred down to the heart wall. The posts do not necessarily have to stand on it, but must have a material under them that can withstand the load. If this material is a side beam in the floor cassette, the total shear force on this should probably be checked.
Developing my question a bit further regarding point 2. Overhanging above and hoping someone wants to answer...
I stated the wrong measurement earlier. The largest opening is 2.1 m. I also probably never mentioned that we have an unfinished cold attic. I would like to have as little beam as possible in the ceiling and therefore wonder if it could be reinforced from the attic instead? Please check my sketch and tell me what you think? Is it completely crazy? How long a plank do you think I would need in the attic/how many roof trusses does it need to span/be attached to? Another dimension? Please see sketch.
Thanks again!
/J
I stated the wrong measurement earlier. The largest opening is 2.1 m. I also probably never mentioned that we have an unfinished cold attic. I would like to have as little beam as possible in the ceiling and therefore wonder if it could be reinforced from the attic instead? Please check my sketch and tell me what you think? Is it completely crazy? How long a plank do you think I would need in the attic/how many roof trusses does it need to span/be attached to? Another dimension? Please see sketch.
Thanks again!
/J
Feels a bit doubtful. Can't you draw up what the roof truss solution looks like?
Fun to have several people who own a small piece of Swedish cultural heritage just like us
Hmm, I'll get back to you, can't access it right now. It is a Mockfjärds element house, so it's such a standard solution (though I can't find any picture...)J justusandersson said:
I kind of don't know how to calculate this, as I'm trying to take part of the load in the attic. (if that's even possible)
Moelven says 90x270 glulam for usual offsetting, but that feels like a lot. Unsure about the load from the attic floor and if it's considered light or normal. Light gives 90x225.
There is an existing opening, originally 1800mm, in the wall that I want to move further in the house, and above that opening, they've only nailed together some 45x95 and it's super stable.
Anyway, here are some measurements I have right now.
From the outer wall to the supporting wall, which is directly above (follows) the central wall/masonry, it is 3750mm.
The attic is an unfinished cold attic with shavings, the roof is 30 degrees and covered with concrete tiles.
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I will check if I have enough just floor plans and a section drawing.
I haven't been able to find such nice drawings on mine
The truss is self-supporting across the entire width of the house. Openings in partition walls do not need to be replaced.
@jesher how did it go?