Manufacture of wooden houses - panels

SIP, prefabricated panels for light and energy efficient houses

Prefabricated self-supporting panels, structural insulated panels, panelized building system or structural insulated sandwich panels are formulations to define the same type of building material - SIP panels.

When I wrote about the different types of wooden houses A reader brought to my attention that there is another type of house that I didn't mention. This is prefabricated panel construction, i.e. SIP panels, which is different from prefabricated structures which we mentioned in our articles. Prefabricated structures are made in a "house factory", which reduces working time on site. Walls are made on a project-by-project basis, varying from house to house. In the case of SIP panels, we are talking about a factory-made building material like other wood-based panels and used by construction companies to erect houses.

SIP are structural insulated panels

SIP stands for the English name of the material - Structural Insulated Panels - and means insulated structural panels. These are sandwich panels that have an insulating material between two structural plates.

The plates are mostly made of OSB building materials, but can also be made of metal, plywood, fibreglass, cement or magnesium oxide. The insulation is the core of the panel and can be expanded polystyrene, extruded polystyrene or rigid polyurethane foam. There are other core variants, but they are less commonly used.

The panels can be used for interior and exterior walls, floors and foundation elements or roofs. They are so constructed that they can be used for any type of building project. The walls are made so that they can also be assembled using similar panels that also contain insulation. This makes the building energy efficient and eliminates the possibility of energy bridges.

Systems have also been developed that allow panels to be produced on site. This further reduces working time. However, factory-made panels have better properties and the quality is the same for all batches.

Based on the idea of insulation inside the panel, eco-panels were also built, which have pressed straw bales as insulation between two plywood boards. These are systems used to build 'green', environmentally friendly and energy-efficient houses.

sip panels
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A little history

The term SIP was introduced in 1935 by the Forest Products Laboratory Madison, USA for panels consisting of a wooden frame with plywood and cardboard on either side and insulation on the inside. These panels were used to build houses that were dismantled after 30 years and analysed for strength and deformations over time.

Their appearance was necessary because, amidst an increased demand for housing and the need for sawn timber, less wood was used to build a house. In addition, the system allowed quick and economical construction, thus lowering the price of houses.

In 1952 Alden B. Dow made the first SIP panel using foam insulation. The panel went into mass production in the 1960s. Such prefabricated panels were used extensively in the USA for house construction before reaching Europe, where the method was later adopted.

Advantages of SIP panels

Panels are presented by many manufacturers and builders as the building material of the 21st century. They believe that the use of SIP panels for the construction of houses or industrial structures comes with advantages for architects, designers and builders as well as for the beneficiaries.

Let's start by looking at some of the qualities of the panels:

  • can be used for the construction of interior and exterior walls, floors and roofs
  • walls built in this way are stronger than those built on wooden structures
  • results in more energy-efficient buildings and 50% than traditional buildings
  • lower values of heat transfer coefficient at lower wall thicknesses
  • can be easily combined with other building materials: bricks, stone, cement, wood, steel, glass
sip panels
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Builders choose to work with SIP panels because:

  • shortens construction time by 2-3 times
  • no need for advanced supervision and increased control during assembly
  • no special tools or equipment required
  • construction costs can be estimated more simply

But the beneficiaries seem to be the happiest, because SIP panels allow for quick construction of lightweight houses. Labour costs will be lower than building a traditional house, and the result will be energy-efficient and sound-insulated homes.

Manufacturers tell us that energy bills are likely to be up to 50-60% lower compared to a similar house made of traditional building materials. In addition, the resilient and resilient construction is considered more earthquake resistant.

The fact that the roof can be built using SIP panels makes it unnecessary to use beams to reinforce the roof. The space will be more airy allowing for mansardisation. The system is also recommended for building dwellings with attic.

prefabricated panels
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There are also disadvantages to consider:

  • buildings constructed with SIP panels may not be higher than 12.5 m
  • expanded and extruded polystyrene are produced with HBCD (hexabrombromocyclododecane), 0 substance considered hazardous by the European Union (REACH program) being classified PBT (persistent, bioaccumulative and toxic)
  • OSB may have formaldehyde emissions. However, there are also low formaldehyde emitting OSB or even class 0 emitting OSB.
  • if OSB is not treated there is a danger of mould and damp
  • walls should be joined at a 90º angle to avoid increasing losses and reducing performance

It is true that many of the disadvantages are highlighted by the manufacturers of other building systems. As a product that is used successfully all over the world, manufacturers have had to adapt and use as 'clean' materials as possible in their production in order to receive the necessary approvals for use in construction. So it is possible to find SIP panels that are free of formaldehyde emissions and contain a non-hazardous insulating foam.

SIP in Romania

The construction system is used and even produced in Romania. A SIP panel factory exists in Clinceni, Ilfov. The manufacturer offers a range of prefabricated panels with thicknesses from 120 to 240 mm, widths from 122 mm to 1250 mm and maximum lengths of 2800 mm and claims that the material has a heat transfer coefficient of 0.022 W/mK.

In addition to panels produced in our country, there are also panels imported from the USA, UK or China.

No matter where they come from, it is clear that SIP panels are a building material for wooden houses that cannot be ignored and therefore added to other existing systems. Despite the perception that OSB panels cannot be considered wood they are still wood and have the advantage of using fast growing, smaller sized and less valuable species.

If the information about prefabricated panels might be useful to others, you can share this article. If you have additions, questions or would like more information, please leave them below in the comments.

sip panels
photo source:

About the author

Mihaela Radu

Mihaela Radu is a chemical engineer but has a great passion for wood. She has been working in the field for more than 20 years, wood finishing being what defined her during this period. She gained experience working in a research institute, in her own company, as well as in a multinational. She wants to continuously share her experience with those who have the same passion - and more.


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  • Very good article (glad you considered my comment). I live in a house built of SIP panels of 60m2 useful heated ground floor (and 40m2 attic) having consumption at -15gr of 12kwh/24 hours. That means an average winter month with heating on electricity is about 120 lei. Temperature in the house of 23gr. Heating is done by a mini-split air conditioner of 12000btu.

    • Hello!
      Thanks for the idea. 🙂 And thanks for the additional information. They are very useful.
      All the best!

      • Think of it like this: 2 sheets of 12mm osb, a 20cm thick expanded polystyrene sheet glued in the press with a polyurethane solution (foam with a low expansion coefficient). The result is a 3m2 panel. Plus labour + profit

      • Lica dear, read carefully. I wrote 12kwh at -15 degrees. I don't know where you live, but we don't have 30 days with this constant temperature. I gave the cost for an average winter month. This is also the way to dimension everything related to heating/cooling (insulation, heating tool, etc.), i.e. according to the average annual temperature of the area you are in. In my house, for example, for winter it's -4gr.

        • Okay, Zoli. I can accept your reasoning. If you can make me a good offer, SIP consisting of 1 sheet osb3 12mm +polystyrene graphite, anti-leakage, 220mm +1sheet MgO 12mm, required 1 pc house 100mp
          + attic, leave a contact and we'll talk.

    • Who was your SIP panel supplier? I'm interested if they also installed them, i.e. they built your house and how much it cost. I really think it's a very good alternative to the traditional house.

    • Hello. I too am interested in building such a house - I am currently researching, reading everything I can find about these panels. Some things are clear......other part..not so much 🙂 For example about the foundation of such a construction. Those who build these houses say that one of the advantages is that there is no need for a deep foundation, that a shallow one is enough because the construction is not heavy. Ok... sounds logical. But another argument found said that.....because the construction is light, if a shallow foundation is used, which does not go down into the ground below the freezing point of the ground, the construction will be subject to movements caused by the freezing and therefore expansion of the ground in winter....and then the thawing of the ground in spring....and that these movements can cause cracks to appear in the finishes at the joints of the boards, both inside and outside. Hmmm....and that sounds logical :).
      And then...

      • Hello everyone and especially Adrian and Alexia,
        I produce structural and thermal insulated panels (SIP) and build houses from them from A to Z in Bihor county, or deliver pre-fabricated structure completely wrapped on modules in other counties.

        We have multiple construction sites in progress and open to visitors in different stages of finishing, so you can see all the processes that are related to this kind of Houses, we do them on the foundation Continue with... or without slab, on pillars, on micropiles, on concrete slabs, trailer or on bricks 🙂

        Besides that we build all in modular system and completely prefabricated from CLT + Basaltic Concrete.

        You can contact me in writing on: "" then also by phone, in Oradea people know me as DoDo

        Even if we don't build you, we can help you with any technical or financial advice if you want to go it alone or with too many disorganized tradesmen to make the best decisions in time! We are and I and the team are very excited with these "new" (to us) lightweight building systems and the energy results at the end of each winter, so gladly and by phone or in writing ask any questions, I will answer concisely; Straightforward.

        • hello. i want to buy SIP panels to build my own house. footprint of the house 75m with attic. please give me a contact where i can talk to you. with esteem Cristi Ionescu

        • good day
          I would like to ask you if I can afford to build my house from structural panels (SIP),
          can you make me the panels for the house on the basis of a project (made by the architect) and on the basis of the same project assemble it for me? I would also like to ask you how long before I have to contact you to schedule the erection of the house (of course after I have the geo study, the project, the permits and the foundation ready)? One more question : according to your experience, what is the cost of a SIP house per m2 (without project, study and foundation costs), at least approximately.
          Waiting for your answer

      • hello. i found your post on a website ...wooden houses. i want to build a house from SIP panels. i would ask you if you are willing to give me a contact to share some advice from your experience. with respect Cristi Ionescu

    • Hi Zoli, what was the price of the red house and with what company did you build the house (or where did you buy the panels and at what price per piece)? Thanks in advance.

  • OSB treatment, interior wall cladding and I think there are a few that price you get CLT and you know a job.
    Does the electrical installation come directly mounted inside in foam?

  • Hi, I've been researching about building a house with sip panels, I read your article and got in touch with the factory you refer to and found out how much it costs. The prices are as follows:
    Material 150-180 euro/sqm
    Red (assembly included) - 250 - 300 euro/sqm
    Turnkey - 550 - 650 euro/sqm
    Prices do not include VAT and transport of materials.
    Much? Little? This was the cheapest price I found on the Romanian SIP panel market.
    Personally I don't want to pay 40 000 for 150m2 in the red for a "temporary" house on one level - ....
    I hope my comment is helpful, all the best!

    • Hi Dan.
      Very good information. Is the factory you got the offer from the one in Clinceni, Ilfov?
      Do they also provide the assembly of the panels and the whole structure?
      And yes, it seems like a lot 300 euro/sqm just for the structure of the house. Is the cost of the foundation and installations included?
      Thanks a lot!

      • Hi, yes the factory in Clinceni, the price of 300 is only for the structure and assembly! it does not include foundation, windows or roof (sheet metal), installations are not even mentioned :)) I looked for information about CLT and I can say that it is 350-400euro for the structure, insulated with insulation and polystyrene. The factory is in Bacau.
        I for one decided to go with 20 gauge poroth. brick, basalt and plasterboard inside/ceiling and polystyrene outside/foundation. The house will be on one level. From my calculations it shouldn't cost nearly as much as sip/clt panels. I will install a ventilation system, quality window joinery, underfloor heating and I think I will get an efficient house. All the best!

        • Hi, I saw your post here and I'm curious if you managed to make the house as you said.
          What was the total cost of the house in red and please tell us how much it cost in grey.
          are very useful information for people who want to start building a house.



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